Prechamber Mod "Flame" Front
Prechamber Mod "Flame" Front
01-26-2011, 02:42 AM
#51
(01-26-2011, 01:22 AM)Captain America It's too bad you cant have a conversation without getting beat down...
It is very late, but I just wanted to make a statement. Everyone, Please do not let him win by refraining from posting what ever your thoughts may be. I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.
I stopped posting over at peach parts because my posts rubbed one member the wrong way and he saw fit to butcher someone else’s thread every time I posted, regardless of what I posted. In this case however, this is MY thread, and I say to hell with him and the computer he hides behind. (Perhaps over the line, but when members are afraid to participate in the forum because of one member, then I say there is a problem.)
Again, everyone please keep posting your thoughts, any thoughts at all, and as for anything he says, just ignore him.
I'll post responses to the technical points in tomorrow.
(01-26-2011, 01:22 AM)Captain America It's too bad you cant have a conversation without getting beat down...
It is very late, but I just wanted to make a statement. Everyone, Please do not let him win by refraining from posting what ever your thoughts may be. I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.
I stopped posting over at peach parts because my posts rubbed one member the wrong way and he saw fit to butcher someone else’s thread every time I posted, regardless of what I posted. In this case however, this is MY thread, and I say to hell with him and the computer he hides behind. (Perhaps over the line, but when members are afraid to participate in the forum because of one member, then I say there is a problem.)
Again, everyone please keep posting your thoughts, any thoughts at all, and as for anything he says, just ignore him.
I'll post responses to the technical points in tomorrow.
01-26-2011, 03:36 AM
#52
(01-26-2011, 02:42 AM)OM616 Please do not let him winThere is nothing to "win". I find it very silly that you think this is some sort of "game".
Quote:by refraining from posting what ever your thoughts may be.I'm not attempting to stop anyone from posting, I'm only trying to ensure that whats posted is not harmful to those that might otherwise consider false information to be "accurate".
Anyone can read this thread. Somebody might read your post and think "Thats a good idea!" then go drill their prechambers and melt a piston.
Quote:I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.Thats a shame. *Information removed to stop somebody from crying.
Quote:In this case however, this is MY threadUm, no. Threads belong to EVERYONE. If you want text to be your own, write a book.
Quote:I'll post responses to the technical points in tomorrow.*Information removed to stop somebody from crying.
![[Image: HitNRun-1.gif]](http://i1229.photobucket.com/albums/ee473/UAofE/HitNRun-1.gif)
This post was last modified: 01-27-2011, 05:10 PM by ForcedInduction.
ForcedInduction
01-26-2011, 03:36 AM
#52
(01-26-2011, 02:42 AM)OM616 Please do not let him winThere is nothing to "win". I find it very silly that you think this is some sort of "game".
Quote:by refraining from posting what ever your thoughts may be.I'm not attempting to stop anyone from posting, I'm only trying to ensure that whats posted is not harmful to those that might otherwise consider false information to be "accurate".
Anyone can read this thread. Somebody might read your post and think "Thats a good idea!" then go drill their prechambers and melt a piston.
Quote:I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.Thats a shame. *Information removed to stop somebody from crying.
Quote:In this case however, this is MY threadUm, no. Threads belong to EVERYONE. If you want text to be your own, write a book.
Quote:I'll post responses to the technical points in tomorrow.*Information removed to stop somebody from crying.
01-26-2011, 07:20 AM
#53
(01-26-2011, 03:36 AM)ForcedInductionPlease .... chill. Let him melt a piston. What do you care? I'll pull another engine for $150 and send it to him. People are responsible for themselves- nearly all of us here wonder why you feel the need to be the idea police.(01-26-2011, 02:42 AM)OM616 Please do not let him winMr. Troll, there is nothing to "win".
2005 CDI heavily modified 1984 300TD - Myna pump/TMIC/enlarged PC's/HX30Super/W126 II front brakes/Vogtland springs/EGT +Boost gauges/H4 Hella's
(01-26-2011, 03:36 AM)ForcedInductionPlease .... chill. Let him melt a piston. What do you care? I'll pull another engine for $150 and send it to him. People are responsible for themselves- nearly all of us here wonder why you feel the need to be the idea police.(01-26-2011, 02:42 AM)OM616 Please do not let him winMr. Troll, there is nothing to "win".
2005 CDI heavily modified 1984 300TD - Myna pump/TMIC/enlarged PC's/HX30Super/W126 II front brakes/Vogtland springs/EGT +Boost gauges/H4 Hella's
01-26-2011, 07:33 AM
#54
Forced, do you know what year the diagram of the prechamber is? ie is it the small hole or one of the later bigger hole?
Higher temp piston crown areas, this would be a good choice for ceramic coating.
I do not have time right now but I do have an extra set of prechambers. One question though, are the glow plug holes in the pre chamber differant sized? My 240 has the larger loop plugs, and the extra pre chambers are 83 pencil plugs
Forced, do you know what year the diagram of the prechamber is? ie is it the small hole or one of the later bigger hole?
Higher temp piston crown areas, this would be a good choice for ceramic coating.
I do not have time right now but I do have an extra set of prechambers. One question though, are the glow plug holes in the pre chamber differant sized? My 240 has the larger loop plugs, and the extra pre chambers are 83 pencil plugs
01-26-2011, 07:53 AM
#55
(01-26-2011, 01:56 AM)ForcedInduction(01-26-2011, 12:50 AM)300D50 If prechambers weren’t so expensive, I'd say one of us should do a dyno run with stock, then another with opened up prechambers, to help quantify the actual difference.
Why use new? They're a penny/5 in the junkyards.
Not here... It's hard to even find a Benz IN a yard, let alone one with the engine...
1990 Power Ram 50 V6 SOHC 24V 6g72
I can be wrong, don't take everything I say as verbatim, please fact-check first.
My posts are my personal opinions and thoughts, unless otherwise noted.
(01-26-2011, 01:56 AM)ForcedInduction(01-26-2011, 12:50 AM)300D50 If prechambers weren’t so expensive, I'd say one of us should do a dyno run with stock, then another with opened up prechambers, to help quantify the actual difference.
Why use new? They're a penny/5 in the junkyards.
Not here... It's hard to even find a Benz IN a yard, let alone one with the engine...
1990 Power Ram 50 V6 SOHC 24V 6g72
I can be wrong, don't take everything I say as verbatim, please fact-check first.
My posts are my personal opinions and thoughts, unless otherwise noted.
01-26-2011, 08:02 AM
#56
(01-26-2011, 03:36 AM)ForcedInduction(01-26-2011, 02:42 AM)OM616 Please do not let him winMr. Troll, there is nothing to "win".
Quote:by refraining from posting what ever your thoughts may be.I'm not attempting to stop anyone from posting, I'm only trying to ensure that whats posted is not harmful to those that might otherwise consider false information to be "accurate".
Anyone can read this thread. Somebody might read your post and think "Thats a good idea!" then go drill their prechambers and melt a piston.
Quote:I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.Thats a shame. "Pussification" has become a major issue around the world.
It's a shame that "Assification" has become a major issue in most forums that you post in/have gotten banned from & used new screennames.
From Forced's 727 transmission thread"Incorrect, you both have failed to understand that lb/ft is a term used as a description of torque.
Please stop polluting my thread with your useless posts."
How come you can call that thread "my", but he can't?
If someone wants to push the limits of the engine, it is theirs to do.
If someone melts their piston, they will learn from it.
I thought this forum was all about pushing the limits. YOU have pushed some limits. At one point, you were the forerunner. Now, you are lagging behind others & I think that is what is causing this rift.
This is a discussion about modifying prechambers & it does not have to do JUST with OM616's 72 HP engine. It is about experimentation. Please let this thread go forward & POSSIBLY expand our knowledge of prechamber dynamics.
Ed
Quote:In this case however, this is MY threadUm, no. Threads belong to EVERYONE. If you want text to be your own, write a book.
Quote:I'll post responses to the technical points in tomorrow.Running away again, seems to be a common issue in your case.
This post was last modified: 01-26-2011, 08:52 AM by yankneck696.
yankneck696
01-26-2011, 08:02 AM #56(01-26-2011, 03:36 AM)ForcedInduction(01-26-2011, 02:42 AM)OM616 Please do not let him winMr. Troll, there is nothing to "win".
Quote:by refraining from posting what ever your thoughts may be.I'm not attempting to stop anyone from posting, I'm only trying to ensure that whats posted is not harmful to those that might otherwise consider false information to be "accurate".
Anyone can read this thread. Somebody might read your post and think "Thats a good idea!" then go drill their prechambers and melt a piston.
Quote:I have received PMs from members from both forums who are, (for lack of a better term), hesitant to post, or just don’t post at all because of one members aggressive attitude.Thats a shame. "Pussification" has become a major issue around the world.
It's a shame that "Assification" has become a major issue in most forums that you post in/have gotten banned from & used new screennames.
From Forced's 727 transmission thread"Incorrect, you both have failed to understand that lb/ft is a term used as a description of torque.
Please stop polluting my thread with your useless posts."
How come you can call that thread "my", but he can't?
If someone wants to push the limits of the engine, it is theirs to do.
If someone melts their piston, they will learn from it.
I thought this forum was all about pushing the limits. YOU have pushed some limits. At one point, you were the forerunner. Now, you are lagging behind others & I think that is what is causing this rift.
This is a discussion about modifying prechambers & it does not have to do JUST with OM616's 72 HP engine. It is about experimentation. Please let this thread go forward & POSSIBLY expand our knowledge of prechamber dynamics.
Ed
Quote:In this case however, this is MY threadUm, no. Threads belong to EVERYONE. If you want text to be your own, write a book.
Quote:I'll post responses to the technical points in tomorrow.Running away again, seems to be a common issue in your case.
01-26-2011, 09:30 AM
#57
(01-25-2011, 08:44 PM)ForcedInductionForced, there is no reason for you to continue to be abusive to other members on this board. I highly recommend you change your tone, clean up your threads or plan on going on a very long vacation from this board.(01-25-2011, 02:57 AM)dieselboy Lol I remember when I thought I knew it all too.dieselchild, try to "remember" what I suggested earlier.
1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42
(01-25-2011, 08:44 PM)ForcedInductionForced, there is no reason for you to continue to be abusive to other members on this board. I highly recommend you change your tone, clean up your threads or plan on going on a very long vacation from this board.(01-25-2011, 02:57 AM)dieselboy Lol I remember when I thought I knew it all too.dieselchild, try to "remember" what I suggested earlier.
1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42
01-26-2011, 11:40 AM
#59
(01-26-2011, 12:14 AM)Hercules My two cents worth.In 1981 mbz increased prechamber hole size,in1982 hole size was reduced back to1981 level. Mbz stated,inorder to reduce piston crown temps. Why the increase in hole size? Mbz was looking for more power. (It did work) ... Not just theory. Only concerns of high piston crown temps. Now in 1985 Mbz again increased hole size to 1981 level,larger size. Have I done this,Yes, does it work,Yes. Noted results,Increased performance, quicker spool,pulls grades in high gear much better. Mbz did it. A little twist,not wanting to go larger than mbz did, I taper reamed all the holes. Larger outside hole smaller inside. Was trying to give flame front a little better direction,to spread more evenly. Results,Little or no smoking. Even wife commented after several months of use,that she had not seen any more smoking after those adjustments.
Well maybe that was three cents worth.
I would have paid a hole dollars worth of cents to have you post that information!!
Seriously, thank you for posting. I like the conical port idea as it helps air get in but doesn’t help the gasses going out. Ideally if the ports could be calibrated so that the amount of pumped air can get in and out of the prechamer with in the time available, however the additional expansion gasses will increase the volume of gasses that need to flow to balance the pressures, which will take longer, prolonging the pressure inside the prechamber. Another way to put it is, 10 people can quickly pass through a door, (compressed air), however it will take 50 people a bit longer to get through the same door, (expansion gasses).
I have not posted 99% of the data that I have from the tests that I have done, most with the assistance of others. I can see that could cause a cloud of skepticism to form over my posts, regardless of the other members that have posted about their modification of their prechambers, none which have reported melting anything. I also attached a scan of the manual I refferenced that did not have hole specs.
In an effort towards full disclosure, I feel it would be appropriate for me to provide some examples of previous experiences in the automotive field.
I attained a Master Auto Certification from the State Of Michigan three months before I graduated from high school. I then went to work for an independent repair shop as a derivability technician.
The management promoted further certification by reimbursing the costs of the tests, and giving a $20 one time bonus for every additional certification a technician earned. Needless to say I started collecting ASE certifications, and when I left that shop to go open my own, I had accumulated 37 ASE certs, many in advanced categories.
A side story; I was sure that I had the record, but the last time I went to a testing center, I decided to talk to a guy that I saw every time I was at the local center, and most of the time at out of town locations, (they only are in the area once a year, so I would go out of town to test more often), and to my dismay I learned that he had 42 certs, not including the three tests that he just took.
I had my own shop for several years and during that time I acquired additional training; Mercury Marine Outboard Factory Trained, Mercury Marine Inboard, (including Diesel), Factory Trained, Yamaha Snowmobile, Motorcycle, and PWC Factory Trained, and a FAA Aircraft Power Plant Ticket. I also was granted an Annual Authorization from the State of Michigan as a instructor in Automotive and Welding Technologies.
I then had an opportunity to go to work for an independent engine developer as a machinist / fabricator in the Instrumentation Department, modifying parts for sensors, making special bolts for strain gauges, Fiber optic scope adaptors etc. I did that for about 10 months, and then was transferred over to the engineering side where I remained for about 5 or so years, until I was transferred to head the Forensic Department. After a year or so, I went to work for GM, which took a big hit and thus I am now back on my own again.
I still have contacts and privileges at the Engine Development Center, even asked for a consult from time to time. The facility is incredible, and the security is tighter than a nuclear reactor, (I have a friend that was a reactor operator for U of M when they had the reactor running).
Anyway, the Instrumentation Department is developing a new temperature sensor in house and they were looking for non-program applications to test it out, I mentioned my little research project and they insisted that I bring the engine in to wire up.
Now, no paper leaves that building unless it is shredded, no camera phones, no memory sticks, no CDs, no lap tops, no Ipods, are allowed past security. Industrial espionage is a very serious subject, there are at any given time at least two different F1 engine programs going on, in addition to Big Three, and Air Craft programs. The security protocols insure the clients that their technology stays confidential. All e-mail is incepted and a individual key is assigned to every clients address, and unless the recipient of an e-mail has the right key, no dice. That prevents accidentally sending information to the wrong address.
Needless to say all my data is in note books with in the compound, and that is where they will stay until they are destroyed. It is kind of a bummer, because I have lots of cool and groovy graphs and what not, but I am going to have to go from memory, and be very careful as to what and how I post any information. It sometimes becomes an issue where the mere mentioning of a measurement result implies that someone out there is capable, and is measuring that specific parameter. So no offence intended when I don't seem forth coming.
Additionally, the fact that other members, Jeemu and Hercules, have posted that they have modified their own, and in Jeemu's case others as well, prechambers and their reports of the result range from, in Jeemu's case not that apparent per butt dyno, (not dynoed yet I don't think), to noticeable improvements in smoke and power (per but dyno), and none of us, my self included here, have melted a piston, (through at least), or destroyed an engine.
Dose that mean that modifying a prechamber as no risks, no, does that mean that there is not a modification drawback that is not apparent with out proper measurement, of cores not. In the beginning I posted that I didn't want to get into this subject in depth because I wanted to wait until I had an engine on my dyno, and data as to the affects of specific degrees of modification. I do enjoy a good technical discussion though, and this thread, despite the tension, has been, and I hope will continue to be, a good technical / theoretical discussion where members post questions and thoughts when they normally would refrain themselves because they think they are not knowledgeable enough to offer anything. That is NEVER the case. Even the simplest of questions or thoughts can spur ideas and create tangent thought strings. Even just posting that you like the thread, or your thoughts about how it would be better encourage continued discussion.
Now moving right along. There seem to be two schools of thought regarding where the majority of fuel is burnt, the cylinder or the prechamber. If I may, Thought #1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine. And #2, those, (myself), that advocate that the prechamber is actually the combustion chamber, or more, a constant / fixed volume combustion chamber, where as much fuel is burned as possible in a fixed area that retains and concentrates heat, maintains a pressurized environment longer than the cylinder to promote complete combustion, and incoming air is directed in a swirl to help dilute and scavenge the remaining post-combustion gasses left over from the previous cycle.
Unfortunately, I have to go for now, but I will continue with my thoughts when I get back.
This post was last modified: 01-27-2011, 07:24 PM by OM616.
Attached Files
Image(s)(01-26-2011, 12:14 AM)Hercules My two cents worth.In 1981 mbz increased prechamber hole size,in1982 hole size was reduced back to1981 level. Mbz stated,inorder to reduce piston crown temps. Why the increase in hole size? Mbz was looking for more power. (It did work) ... Not just theory. Only concerns of high piston crown temps. Now in 1985 Mbz again increased hole size to 1981 level,larger size. Have I done this,Yes, does it work,Yes. Noted results,Increased performance, quicker spool,pulls grades in high gear much better. Mbz did it. A little twist,not wanting to go larger than mbz did, I taper reamed all the holes. Larger outside hole smaller inside. Was trying to give flame front a little better direction,to spread more evenly. Results,Little or no smoking. Even wife commented after several months of use,that she had not seen any more smoking after those adjustments.
Well maybe that was three cents worth.
I would have paid a hole dollars worth of cents to have you post that information!!
Seriously, thank you for posting. I like the conical port idea as it helps air get in but doesn’t help the gasses going out. Ideally if the ports could be calibrated so that the amount of pumped air can get in and out of the prechamer with in the time available, however the additional expansion gasses will increase the volume of gasses that need to flow to balance the pressures, which will take longer, prolonging the pressure inside the prechamber. Another way to put it is, 10 people can quickly pass through a door, (compressed air), however it will take 50 people a bit longer to get through the same door, (expansion gasses).
I have not posted 99% of the data that I have from the tests that I have done, most with the assistance of others. I can see that could cause a cloud of skepticism to form over my posts, regardless of the other members that have posted about their modification of their prechambers, none which have reported melting anything. I also attached a scan of the manual I refferenced that did not have hole specs.
In an effort towards full disclosure, I feel it would be appropriate for me to provide some examples of previous experiences in the automotive field.
I attained a Master Auto Certification from the State Of Michigan three months before I graduated from high school. I then went to work for an independent repair shop as a derivability technician.
The management promoted further certification by reimbursing the costs of the tests, and giving a $20 one time bonus for every additional certification a technician earned. Needless to say I started collecting ASE certifications, and when I left that shop to go open my own, I had accumulated 37 ASE certs, many in advanced categories.
A side story; I was sure that I had the record, but the last time I went to a testing center, I decided to talk to a guy that I saw every time I was at the local center, and most of the time at out of town locations, (they only are in the area once a year, so I would go out of town to test more often), and to my dismay I learned that he had 42 certs, not including the three tests that he just took.
I had my own shop for several years and during that time I acquired additional training; Mercury Marine Outboard Factory Trained, Mercury Marine Inboard, (including Diesel), Factory Trained, Yamaha Snowmobile, Motorcycle, and PWC Factory Trained, and a FAA Aircraft Power Plant Ticket. I also was granted an Annual Authorization from the State of Michigan as a instructor in Automotive and Welding Technologies.
I then had an opportunity to go to work for an independent engine developer as a machinist / fabricator in the Instrumentation Department, modifying parts for sensors, making special bolts for strain gauges, Fiber optic scope adaptors etc. I did that for about 10 months, and then was transferred over to the engineering side where I remained for about 5 or so years, until I was transferred to head the Forensic Department. After a year or so, I went to work for GM, which took a big hit and thus I am now back on my own again.
I still have contacts and privileges at the Engine Development Center, even asked for a consult from time to time. The facility is incredible, and the security is tighter than a nuclear reactor, (I have a friend that was a reactor operator for U of M when they had the reactor running).
Anyway, the Instrumentation Department is developing a new temperature sensor in house and they were looking for non-program applications to test it out, I mentioned my little research project and they insisted that I bring the engine in to wire up.
Now, no paper leaves that building unless it is shredded, no camera phones, no memory sticks, no CDs, no lap tops, no Ipods, are allowed past security. Industrial espionage is a very serious subject, there are at any given time at least two different F1 engine programs going on, in addition to Big Three, and Air Craft programs. The security protocols insure the clients that their technology stays confidential. All e-mail is incepted and a individual key is assigned to every clients address, and unless the recipient of an e-mail has the right key, no dice. That prevents accidentally sending information to the wrong address.
Needless to say all my data is in note books with in the compound, and that is where they will stay until they are destroyed. It is kind of a bummer, because I have lots of cool and groovy graphs and what not, but I am going to have to go from memory, and be very careful as to what and how I post any information. It sometimes becomes an issue where the mere mentioning of a measurement result implies that someone out there is capable, and is measuring that specific parameter. So no offence intended when I don't seem forth coming.
Additionally, the fact that other members, Jeemu and Hercules, have posted that they have modified their own, and in Jeemu's case others as well, prechambers and their reports of the result range from, in Jeemu's case not that apparent per butt dyno, (not dynoed yet I don't think), to noticeable improvements in smoke and power (per but dyno), and none of us, my self included here, have melted a piston, (through at least), or destroyed an engine.
Dose that mean that modifying a prechamber as no risks, no, does that mean that there is not a modification drawback that is not apparent with out proper measurement, of cores not. In the beginning I posted that I didn't want to get into this subject in depth because I wanted to wait until I had an engine on my dyno, and data as to the affects of specific degrees of modification. I do enjoy a good technical discussion though, and this thread, despite the tension, has been, and I hope will continue to be, a good technical / theoretical discussion where members post questions and thoughts when they normally would refrain themselves because they think they are not knowledgeable enough to offer anything. That is NEVER the case. Even the simplest of questions or thoughts can spur ideas and create tangent thought strings. Even just posting that you like the thread, or your thoughts about how it would be better encourage continued discussion.
Now moving right along. There seem to be two schools of thought regarding where the majority of fuel is burnt, the cylinder or the prechamber. If I may, Thought #1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine. And #2, those, (myself), that advocate that the prechamber is actually the combustion chamber, or more, a constant / fixed volume combustion chamber, where as much fuel is burned as possible in a fixed area that retains and concentrates heat, maintains a pressurized environment longer than the cylinder to promote complete combustion, and incoming air is directed in a swirl to help dilute and scavenge the remaining post-combustion gasses left over from the previous cycle.
Unfortunately, I have to go for now, but I will continue with my thoughts when I get back.
Attached Files
Image(s)
01-26-2011, 02:52 PM
#60
Hercules, do you have info on what size holes Mercedes used in 81 vs 82? What size did you ream your holes to? If we can compare the sizes, that may be of help as well.
Either way, please keep up the good work and discussion!
82 300SD aka The Flyin Pumpkin (Gone): 7.5mm super M-pump, T3 60 trim turbo, Coldish air intake, A/W intercooler, propane injection, SW Boost and EGT gauges, Monark 265 nozzles, ported/polished cylinder head.
84 Euro 300D 4 sp: White with black trunk and hood. Blue cloth interior. Manual everything. 300DT front swaybar. C320 17" wheels. Now with the Flyin Pumpkins engine!
I am following this thread pretty closely. I was a tech for years, and love hot rodding stuff, but have no degree or advanced technical training. I have a spare cylinder head from my SD, and am considering doing this mod to the prechambers. However, I am also waiting to see what people with better resources and facilities come up with for proven hole sizes/shapes. If its a matter of drill it and try it I may end up getting to that point, but not for a while.
Hercules, do you have info on what size holes Mercedes used in 81 vs 82? What size did you ream your holes to? If we can compare the sizes, that may be of help as well.
Either way, please keep up the good work and discussion!
82 300SD aka The Flyin Pumpkin (Gone): 7.5mm super M-pump, T3 60 trim turbo, Coldish air intake, A/W intercooler, propane injection, SW Boost and EGT gauges, Monark 265 nozzles, ported/polished cylinder head.
84 Euro 300D 4 sp: White with black trunk and hood. Blue cloth interior. Manual everything. 300DT front swaybar. C320 17" wheels. Now with the Flyin Pumpkins engine!
01-26-2011, 05:29 PM
#61
I am more inclined to agree with thought #1 (what Forced said), that it is a "Pre-Combustion Chamber" and the combustion is started here and continues into the cylinder. Why does it have to begin here? Hell if I know!
Not really knowing anything else sucks, but Reading this has enlightened me of both sides of the story. I WILL play with the hole sizes on the extra set that I have when the time comes....
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-26-2011, 05:29 PM #61I am following as well. Very good thread.
I am more inclined to agree with thought #1 (what Forced said), that it is a "Pre-Combustion Chamber" and the combustion is started here and continues into the cylinder. Why does it have to begin here? Hell if I know!
Not really knowing anything else sucks, but Reading this has enlightened me of both sides of the story. I WILL play with the hole sizes on the extra set that I have when the time comes....
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-26-2011, 07:33 PM
#62
This post was last modified: 01-26-2011, 07:33 PM by MTUPower.
2005 CDI heavily modified 1984 300TD - Myna pump/TMIC/enlarged PC's/HX30Super/W126 II front brakes/Vogtland springs/EGT +Boost gauges/H4 Hella's
I'll be headed to the yards here in Feb to pull a wagon head for modification. I need more power and less smoke in my wagon, and will be doing quite a bit in search of that goal. A VGT install is high on the list, but every little bit helps. With a spare head I can compare apples to apples with few other variables.
2005 CDI heavily modified 1984 300TD - Myna pump/TMIC/enlarged PC's/HX30Super/W126 II front brakes/Vogtland springs/EGT +Boost gauges/H4 Hella's
01-26-2011, 07:45 PM
#63
Just a thought, but if the holes leading out of the prechamber were to be enlarged, this would allow for the flame front to travel more quickly. therefore wouldn't the timing have to be adjusted? Also would the timing advance device on out engines be able to cope as there would be a new timing curve?
01-26-2011, 08:47 PM
#64
OM 616,(or anyone know might know) do you know if newer chambers will fit my 77 240d ? I have a set from an 83 300 that I could pull for testing.
I have always thought the pre chamber is there to start combustion. One thing that I know from studying combustion, primary in boilers, is that you need X amount of space to properly burn a given amount of fuel. Off the top of my head it would appear there is not enough space to cleanly burn enough fuel in the pre chamber. If most of the fuel were to be burnt in the pre chamber then the pressures would have to be very high in order to fill the cylinder and still have enough force to push the piston down. On the other hand if the pre chamber is just a starting point for combustion then the rest of the fuel is burned in the cylinder you will have a more even pressure between the two, and much more space to burn the fuel. So I lean toward no 1 theory.
OM 616,(or anyone know might know) do you know if newer chambers will fit my 77 240d ? I have a set from an 83 300 that I could pull for testing.
01-26-2011, 11:40 PM
#65
(01-26-2011, 08:47 PM)ronnie I have always thought the pre chamber is there to start combustion. One thing that I know from studying combustion, primary in boilers, is that you need X amount of space to properly burn a given amount of fuel. Off the top of my head it would appear there is not enough space to cleanly burn enough fuel in the pre chamber. If most of the fuel were to be burnt in the pre chamber then the pressures would have to be very high in order to fill the cylinder and still have enough force to push the piston down. On the other hand if the pre chamber is just a starting point for combustion then the rest of the fuel is burned in the cylinder you will have a more even pressure between the two, and much more space to burn the fuel. So I lean toward no 1 theory.
OM 616,(or anyone know might know) do you know if newer chambers will fit my 77 240d ? I have a set from an 83 300 that I could pull for testing.
No, they are not interchangeable. There are two types of prechambers for the 616, each one requires a piston that is matched for it.
I have a 78 616 and we both have the pre-uprated prechambers with the flat bottom. When MB increased the HP they also beefed up the end of the prechamber and it sticks down farther and the pocket in the piston is deeper and shaped differently. If you put the newer prechambers in an older engine, the piston will hit the prechamber.
I have a set of the uprated prechambers that I am going to put in my 78, but I am going to make a tool to machine the pocket in the piston through the prechamber hole in the head, so the piston won't hit the uprated prechamber.
I am working on the other half of my thought, and I want to post it in one shot instead of bits here and there. I have the portion of the thought that pertains to #1 almost done. I need to add some, take some away, and proof it a couple of times, then to #2. I am having some difficulty putting words to what I see in my head. I am busy this week, so I will work on it as time allows.
Again, don't hesitate to post!!
(01-26-2011, 08:47 PM)ronnie I have always thought the pre chamber is there to start combustion. One thing that I know from studying combustion, primary in boilers, is that you need X amount of space to properly burn a given amount of fuel. Off the top of my head it would appear there is not enough space to cleanly burn enough fuel in the pre chamber. If most of the fuel were to be burnt in the pre chamber then the pressures would have to be very high in order to fill the cylinder and still have enough force to push the piston down. On the other hand if the pre chamber is just a starting point for combustion then the rest of the fuel is burned in the cylinder you will have a more even pressure between the two, and much more space to burn the fuel. So I lean toward no 1 theory.
OM 616,(or anyone know might know) do you know if newer chambers will fit my 77 240d ? I have a set from an 83 300 that I could pull for testing.
No, they are not interchangeable. There are two types of prechambers for the 616, each one requires a piston that is matched for it.
I have a 78 616 and we both have the pre-uprated prechambers with the flat bottom. When MB increased the HP they also beefed up the end of the prechamber and it sticks down farther and the pocket in the piston is deeper and shaped differently. If you put the newer prechambers in an older engine, the piston will hit the prechamber.
I have a set of the uprated prechambers that I am going to put in my 78, but I am going to make a tool to machine the pocket in the piston through the prechamber hole in the head, so the piston won't hit the uprated prechamber.
I am working on the other half of my thought, and I want to post it in one shot instead of bits here and there. I have the portion of the thought that pertains to #1 almost done. I need to add some, take some away, and proof it a couple of times, then to #2. I am having some difficulty putting words to what I see in my head. I am busy this week, so I will work on it as time allows.
Again, don't hesitate to post!!
01-26-2011, 11:42 PM
#66
(01-26-2011, 02:52 PM)Biohazard I am following this thread pretty closely. I was a tech for years, and love hot rodding stuff, but have no degree or advanced technical training. I have a spare cylinder head from my SD, and am considering doing this mod to the prechambers. However, I am also waiting to see what people with better resources and facilities come up with for proven hole sizes/shapes. If its a matter of drill it and try it I may end up getting to that point, but not for a while.
Hercules, do you have info on what size holes Mercedes used in 81 vs 82? What size did you ream your holes to? If we can compare the sizes, that may be of help as well.
Either way, please keep up the good work and discussion!
Biohazard, I hope the attachments come through. Sorry guys I was off one year, in 1981 they reduced the hole size from 1980. But then in 1985 they increased it back to the 1980 size. They only changed two burner holes K and L were reduced, all others remained the same. K burner hole went from 2.0 mm in 1980 to 1.5 mm in 1981, and L went from 3.5 mm in 1980 to 3.2 mm in 1981. Can use the larger burner hole size in all 80 -85 diesels.
My reason for tapering the holes was to see if I could reduce the smoking, knowing that everything happens so fast, that I reasoned that starting the direction of the flame coming out of the prechamber might increase the burn area more quickly. The flame in motion, in the direction it needs to go would continue in a more improved area. Sure seemed to work, power level improved and smoking decreased. Starts instantly, runs smoothly, and accelerates smoothly. It works for me!!
I got the tools I used from JISCO. Small is SM-1 DC, next size SL-2 D/C, Large tool is a 1/8th - 1/2 reamer, shortest is 1/2 inch champher bit. Using each size, according to hole size. Ream until inner base size just begins to enlarge. Use back side of matching drill for checking the hole, then champher outside lip. I did all this by hand so that I wouldn't over shoot.
More penny's for thought.
(01-26-2011, 02:52 PM)Biohazard I am following this thread pretty closely. I was a tech for years, and love hot rodding stuff, but have no degree or advanced technical training. I have a spare cylinder head from my SD, and am considering doing this mod to the prechambers. However, I am also waiting to see what people with better resources and facilities come up with for proven hole sizes/shapes. If its a matter of drill it and try it I may end up getting to that point, but not for a while.
Hercules, do you have info on what size holes Mercedes used in 81 vs 82? What size did you ream your holes to? If we can compare the sizes, that may be of help as well.
Either way, please keep up the good work and discussion!
Biohazard, I hope the attachments come through. Sorry guys I was off one year, in 1981 they reduced the hole size from 1980. But then in 1985 they increased it back to the 1980 size. They only changed two burner holes K and L were reduced, all others remained the same. K burner hole went from 2.0 mm in 1980 to 1.5 mm in 1981, and L went from 3.5 mm in 1980 to 3.2 mm in 1981. Can use the larger burner hole size in all 80 -85 diesels.
My reason for tapering the holes was to see if I could reduce the smoking, knowing that everything happens so fast, that I reasoned that starting the direction of the flame coming out of the prechamber might increase the burn area more quickly. The flame in motion, in the direction it needs to go would continue in a more improved area. Sure seemed to work, power level improved and smoking decreased. Starts instantly, runs smoothly, and accelerates smoothly. It works for me!!
I got the tools I used from JISCO. Small is SM-1 DC, next size SL-2 D/C, Large tool is a 1/8th - 1/2 reamer, shortest is 1/2 inch champher bit. Using each size, according to hole size. Ream until inner base size just begins to enlarge. Use back side of matching drill for checking the hole, then champher outside lip. I did all this by hand so that I wouldn't over shoot.
More penny's for thought.
01-27-2011, 12:31 AM
#67
What did the tools cost you Herc?
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-27-2011, 12:31 AM #67That sounds freaking good to me!
What did the tools cost you Herc?
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-27-2011, 03:32 AM
#68
82 300SD aka The Flyin Pumpkin (Gone): 7.5mm super M-pump, T3 60 trim turbo, Coldish air intake, A/W intercooler, propane injection, SW Boost and EGT gauges, Monark 265 nozzles, ported/polished cylinder head.
84 Euro 300D 4 sp: White with black trunk and hood. Blue cloth interior. Manual everything. 300DT front swaybar. C320 17" wheels. Now with the Flyin Pumpkins engine!
Thanks Hercules! The attachments came through just fine after I downloaded some new software. Haha! Thanks for the info, thats what I was looking to see. So am I correct to assume you did this to all the holes?
82 300SD aka The Flyin Pumpkin (Gone): 7.5mm super M-pump, T3 60 trim turbo, Coldish air intake, A/W intercooler, propane injection, SW Boost and EGT gauges, Monark 265 nozzles, ported/polished cylinder head.
84 Euro 300D 4 sp: White with black trunk and hood. Blue cloth interior. Manual everything. 300DT front swaybar. C320 17" wheels. Now with the Flyin Pumpkins engine!
01-27-2011, 04:38 AM
#69
(01-27-2011, 12:31 AM)Captain America That sounds freaking good to me!
What did the tools cost you Herc?
approx.tool cost $40.00,or less The large tool is made by Blue Point,#R120,1/8-1/2 pipe reamer.Most hardware stores should carry some brand of this tool. The chamfer tool is by Stanley,1/2"size very common.The two smaller tools are grinding burrs,double cut. Single cut cost less. These are usually order items or from industrial warehouse.
(01-27-2011, 03:32 AM)Biohazard Thanks Hercules! The attachments came through just fine after I downloaded some new software. Haha! Thanks for the info, thats what I was looking to see. So am I correct to assume you did this to all the holes?
Yes,Did this to all .
Read some of the members were pondering if increasing hole "o" ,prechamber neck bore. Tryed this also,Result more smoking. Seems that the fuel is less atomized. ( Learning is trying ) Lucky me,owned and managed a mercedes shop.
This post was last modified: 01-27-2011, 05:01 AM by Hercules.
(01-27-2011, 12:31 AM)Captain America That sounds freaking good to me!
What did the tools cost you Herc?
approx.tool cost $40.00,or less The large tool is made by Blue Point,#R120,1/8-1/2 pipe reamer.Most hardware stores should carry some brand of this tool. The chamfer tool is by Stanley,1/2"size very common.The two smaller tools are grinding burrs,double cut. Single cut cost less. These are usually order items or from industrial warehouse.
(01-27-2011, 03:32 AM)Biohazard Thanks Hercules! The attachments came through just fine after I downloaded some new software. Haha! Thanks for the info, thats what I was looking to see. So am I correct to assume you did this to all the holes?
Yes,Did this to all .
Read some of the members were pondering if increasing hole "o" ,prechamber neck bore. Tryed this also,Result more smoking. Seems that the fuel is less atomized. ( Learning is trying ) Lucky me,owned and managed a mercedes shop.
01-27-2011, 05:03 PM
#70
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-27-2011, 05:03 PM #70Smoking is only good when you have the ponies to back it up!
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-27-2011, 05:36 PM
#71
If the prechamber is only a delivery method, (an extension of the injector), for fuel to get into the cylinder, where it is ignited and burnt (like a DI engine), how would the prechamber effect the combustion environment in the cylinder to allow the engine to rev faster than a DI engine?
While I am putting together my thoughts I will pose this question that relates to theory #1. (see post #59 for theory)
If the prechamber is only a delivery method, (an extension of the injector), for fuel to get into the cylinder, where it is ignited and burnt (like a DI engine), how would the prechamber effect the combustion environment in the cylinder to allow the engine to rev faster than a DI engine?
01-27-2011, 05:39 PM
#72
(01-26-2011, 11:40 AM)OM616 Another way to put it is, 10 people can quickly pass through a door, (compressed air), however it will take 50 people a bit longer to get through the same door, (expansion gasses).Thats not how the prechamber works.
OM616, can you skip the life "story" please.
Quote:#1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine.That is the correct description.
Quote:And #2, those, (myself), that advocate that the prechamber is actually the combustion chamber, or more, a constant / fixed volume combustion chamber, where as much fuel is burned as possible in a fixed area that retains and concentrates heat, and incoming air is directed in a swirl to help dilute and scavenge the remaining post-combustion gasses left over from the previous cycle.Incorrect.
(01-27-2011, 05:03 PM)Captain America Smoking is only good when you have the ponies to back it up!Smoke is never good. Anything more than a slight haze is power dumped out the tailpipe.
ForcedInduction
01-27-2011, 05:39 PM
#72
(01-26-2011, 11:40 AM)OM616 Another way to put it is, 10 people can quickly pass through a door, (compressed air), however it will take 50 people a bit longer to get through the same door, (expansion gasses).Thats not how the prechamber works.
OM616, can you skip the life "story" please.
Quote:#1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine.That is the correct description.
Quote:And #2, those, (myself), that advocate that the prechamber is actually the combustion chamber, or more, a constant / fixed volume combustion chamber, where as much fuel is burned as possible in a fixed area that retains and concentrates heat, and incoming air is directed in a swirl to help dilute and scavenge the remaining post-combustion gasses left over from the previous cycle.Incorrect.
(01-27-2011, 05:03 PM)Captain America Smoking is only good when you have the ponies to back it up!Smoke is never good. Anything more than a slight haze is power dumped out the tailpipe.
01-27-2011, 07:16 PM
#73
(01-27-2011, 05:39 PM)ForcedInduction [quote='OM616' pid='23652' dateline='1296060040']Another way to put it ...
Quote:#1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine.That is the correct description.
...
My understanding is the pre-chamber causes turbulence and swirl to what ever fuel or mixture comes out of it.
In terms of just fuel just coming out of it, I think I need a little help in understanding of how that would work. How can 135 bar injected fuel can create this so called turbulence. I think it cannot create it without fuel or some of the fuel being burnt in the chamber and that fast burning expansion creates the turbulence.
.
.
Gota love Mercedes Diesels!
.
DeliveryValve
01-27-2011, 07:16 PM #73(01-27-2011, 05:39 PM)ForcedInduction [quote='OM616' pid='23652' dateline='1296060040']Another way to put it ...
Quote:#1), those advocating that the fuel is burnt in the cylinder, contend that in essence, the prechambre is strictly an extension of the injector nozzle that conditions the fuel into a more burnable form and disperses the conditioned fuel throughout the cylinder where it then ignites and burns like a DI engine.That is the correct description.
...
My understanding is the pre-chamber causes turbulence and swirl to what ever fuel or mixture comes out of it.
In terms of just fuel just coming out of it, I think I need a little help in understanding of how that would work. How can 135 bar injected fuel can create this so called turbulence. I think it cannot create it without fuel or some of the fuel being burnt in the chamber and that fast burning expansion creates the turbulence.
.
.
Gota love Mercedes Diesels!
.
01-27-2011, 07:44 PM
#74
1977 300D for parts? Just a pile of rust but still runs!
1984 190D 2.2 - gone to better home
1987 Dodge Maxivan with OM603 and Goran’s 7.5 backroads terror
1987 300TD - tinker toy
1989 300TE - parts
1991 300TE - backyards decor
1991 300TD - Barrote’s 7.5
1992 300TD - semi-STD(Goran modified 7.5 ip but still with factory turbo+at)
1998 E300TD - dd with DSL1 now
1998 ML320 - snow ride
2014 Sprinter 2500 - Malone’s tune + pedal box
Looks to me discussion here is like trying to reinvent the wheel. Principle of operation of precumbustion chamber are well establish for over hundred years. In practical application is to containe combustion in small space to allow better control of expanssion of gases. In passanger cars pre cup engines are used do to it more quite operation.
1977 300D for parts? Just a pile of rust but still runs!
1984 190D 2.2 - gone to better home
1987 Dodge Maxivan with OM603 and Goran’s 7.5 backroads terror
1987 300TD - tinker toy
1989 300TE - parts
1991 300TE - backyards decor
1991 300TD - Barrote’s 7.5
1992 300TD - semi-STD(Goran modified 7.5 ip but still with factory turbo+at)
1998 E300TD - dd with DSL1 now
1998 ML320 - snow ride
2014 Sprinter 2500 - Malone’s tune + pedal box
01-27-2011, 07:45 PM
#75
Given that #1 is getting the most votes, I have decided to post my thoughts regarding #1 to see if I am missing something that may sway me from my #2 position.
My apologies if I don’t make sense, I am multitasking and don’t have the time to have it proof read by others, so I thought everyone here could proof read it for me.
Although I am an advocate of the #2 theory, I will do my best to impartially lay out my thoughts regarding how theory #1 would work, remember this is from my personal perspective and I am open to counter arguments of any sort. Here we go.
I have not measured the volume of the prechamber, either the 61X or 60X, but I do have a good idea of the size and shape of the chamber, the ID of the burn tube, and the distance from the nozzle to the tip of the burn tube. This is important to me because of what has to happen in order for the fuel that is injected into the prechamber, to be expelled from the burn holes into the cylinder, to ignite.
Another important volume to me is the amount of fuel that is injected, and how long does the injection last. For example, if at idle, the IP puts out 1cc every 1000 revolutions of the IP, that would equal .001 CCs of fuel injected per injection cycle at idle. Now that .001cc of fuel is injected into the prechamber in a fine mist creating a fog of fuel as apposed to a stream, the point being that a fog disperses and a stream has a trajectory.
Lets say for simplicity, that the distance from the injector nozzle to the bottom of the burn holes is 2 inches, (it is a little more than, but 2 is a nice number). The fog of fuel that is injected into the prechamber needs to, per the #1 theory, be heated to further atomize the fuel, and propelled through the oval chamber it self, down the burn tube, and out the small holes with enough velocity to disperse the fuel throughout the cylinder where it then ignites.
It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.
This is where I have a problem visualizing how this would actually be able to happen. For example, if only a very small portion of air is allowed to enter the prechamber, then the prechamber pressure will be lower than the cylinder pressure, and the less air that can get into the prechamber, the grater the pressure differential.
Sticking with pressure portion of the #1 optional theory, in order for anything to be expelled from the prechamber burn holes, there needs to be a higher inside the prechamber, than the pressure in the cylinder. In other words, pressure naturally wants to be equal or balanced, if you have a flat tire and a portable air tank, the air will leave the higher pressure tank, and go into the lower pressure tire. This will continue until the pressure in the tank and the pressure in the tire are equal, and at that point, the flow of air will stop. The same thing would take place in respect to the prechamber and cylinder pressures, only the prechamber starts off at a lower pressure than the cylinder, quite a bit lower because of the small holes.
Now considering the order of operations that would result in warmed, non-ignited fuel, to be blown into the cylinder, wouldn’t all the fuel need to be injected into the prechamber before a small portion of it is ignited? The heat from the combustion would then warm the rest of the fuel, and increases the pressure inside the prechamber high enough to cause the prechamber and cylinder pressures to try to balance each other, resulting in gasses and fuel being expelled from the prechamber into the cylinder, where it can then burn.
A couple of concerns come to my mind given that sequence of events. First, what ignites the fuel, or more correctly stated, what prevents the fuel from igniting in the prechamber, until after all the fuel is injected into the prechamber? If the initial portion of fuel injected into the prechamber ignited and then went out, the remaining fuel that is injected would be on the wrong side of the pressure wave wouldn’t it?
Also, what keeps all the fuel from burning in the prechamber? Is it a lack of oxygen because very little air is allowed to enter the prechamber during compression? That would be very dirty as the flame would smother out causing lots of CO. I also have an issue with the idea that the main quantity of fuel is blown into the cylinder to ignite and burn, would that not tend to nail like mad, (like a DI engine), as there would be a large amount of fuel ignited, vrs the fuel igniting as it is injected?
And another thing, if the combustion chamber is in the cylinder, and not the prechamber, how does the prechamber have any affect the ability of the engine to rev faster than a DI engine?
Statement (A) of theory #1
The cylinder pressure is always higher than the prechamber pressure, (pre-injection), because of the small holes restricting air flow into the prechamber. Fuel is dispersed from the prechamber and throughout the cylinder to be burnt, by a pressure differential created by a small amount of fuel that is burnt in the prechamber, which raises the prechamber pressure above the cylinder pressure, causing gasses to flow from the prechamber to the cylinder.
Thought pertaining to Statement (A) of theory #1;
If, per theory #1, the majority of fuel is burnt in the cylinder, then the pressure in the cylinder will quickly become higher than the pressure in the prechamber when the fuel ignites. This pressure differential would cause flow from the cylinder into the prechamber.
If there is only enough air in the prechamber to support the initial combustion of the small amount of fuel that propelled the fuel into the cylinder to begin with, then unless all the fuel has made it into the cylinder before it ignites, any fuel that is flowing out of the prechamber will be pushed back into the prechamber in an effort to balance the higher cylinder and lower prechamber pressures, and any flame would be smothered out once it entered the prechamber, then expelled back into the cylinder once the cylinder pressure drops bellow the prechamber pressure. This would produce lots of partially brunt fuel, CO, not a good emission.
Even if the fuel gradually ignited as it leaves the prehamber, the moment the cylinder pressure is equal to, or higher than, the prehamber pressure, the fuel will stop flowing from the prechamber to the cylinder, and the fire will go out because there is not enough air in the prechamber to sustain combustion.
Because the air in the prechamber was used up during the initial push, another burst of pressure from combustion in the prehchamber can not be possible unless additional air from the cylinder is forced into the prechamber, allowing another burst that will push a second wave of fuel into the cylinder until the pressures switch again. This would cause multiple ignitions in the cylinder as the main portion of the fuel would be expelled from the prechamber in pulses, as the cylinder and prechamber trade high and low pressure states
Keeping in mind that the start of injection takes place before TDC, and therefore the cylinder pressure is continually rising from compression, before and during, the duration of the injection. With out a continuously higher pressure in the prechamber than the cylinder, a sustained dispersion of fuel into the constantly increasing pressures of the cylinder is not possible, as flow is from high pressure to low pressure.
Unless the prechamber pressure is constantly increasing, maintaining a higher pressure than the cylinder pressure throughout the entire injection and combustion cycle, then I do not see how a continuous flame front can be maintained in the cylinder.
Additionally, there seems to be a consensus that the prechambers ability to maintain a high pressure longer than the cylinder, allows the IDI engine to rev higher than a DI engine. If that is the case, and the majority of the fuel is burned in the cylinder and not the prechamber, then how does the pressure in the prechamber, (that does not contain any burning fuel because the little amount of air that was allowed to enter the prechamber was used up during the pulse sequence of the injection), have anything to do with the combustion environment in the cylinder? Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?
OK, I added to #2s list of goodness. (See post #59 for theories #1 and #2.)
Given that #1 is getting the most votes, I have decided to post my thoughts regarding #1 to see if I am missing something that may sway me from my #2 position.
My apologies if I don’t make sense, I am multitasking and don’t have the time to have it proof read by others, so I thought everyone here could proof read it for me.
Although I am an advocate of the #2 theory, I will do my best to impartially lay out my thoughts regarding how theory #1 would work, remember this is from my personal perspective and I am open to counter arguments of any sort. Here we go.
I have not measured the volume of the prechamber, either the 61X or 60X, but I do have a good idea of the size and shape of the chamber, the ID of the burn tube, and the distance from the nozzle to the tip of the burn tube. This is important to me because of what has to happen in order for the fuel that is injected into the prechamber, to be expelled from the burn holes into the cylinder, to ignite.
Another important volume to me is the amount of fuel that is injected, and how long does the injection last. For example, if at idle, the IP puts out 1cc every 1000 revolutions of the IP, that would equal .001 CCs of fuel injected per injection cycle at idle. Now that .001cc of fuel is injected into the prechamber in a fine mist creating a fog of fuel as apposed to a stream, the point being that a fog disperses and a stream has a trajectory.
Lets say for simplicity, that the distance from the injector nozzle to the bottom of the burn holes is 2 inches, (it is a little more than, but 2 is a nice number). The fog of fuel that is injected into the prechamber needs to, per the #1 theory, be heated to further atomize the fuel, and propelled through the oval chamber it self, down the burn tube, and out the small holes with enough velocity to disperse the fuel throughout the cylinder where it then ignites.
It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.
This is where I have a problem visualizing how this would actually be able to happen. For example, if only a very small portion of air is allowed to enter the prechamber, then the prechamber pressure will be lower than the cylinder pressure, and the less air that can get into the prechamber, the grater the pressure differential.
Sticking with pressure portion of the #1 optional theory, in order for anything to be expelled from the prechamber burn holes, there needs to be a higher inside the prechamber, than the pressure in the cylinder. In other words, pressure naturally wants to be equal or balanced, if you have a flat tire and a portable air tank, the air will leave the higher pressure tank, and go into the lower pressure tire. This will continue until the pressure in the tank and the pressure in the tire are equal, and at that point, the flow of air will stop. The same thing would take place in respect to the prechamber and cylinder pressures, only the prechamber starts off at a lower pressure than the cylinder, quite a bit lower because of the small holes.
Now considering the order of operations that would result in warmed, non-ignited fuel, to be blown into the cylinder, wouldn’t all the fuel need to be injected into the prechamber before a small portion of it is ignited? The heat from the combustion would then warm the rest of the fuel, and increases the pressure inside the prechamber high enough to cause the prechamber and cylinder pressures to try to balance each other, resulting in gasses and fuel being expelled from the prechamber into the cylinder, where it can then burn.
A couple of concerns come to my mind given that sequence of events. First, what ignites the fuel, or more correctly stated, what prevents the fuel from igniting in the prechamber, until after all the fuel is injected into the prechamber? If the initial portion of fuel injected into the prechamber ignited and then went out, the remaining fuel that is injected would be on the wrong side of the pressure wave wouldn’t it?
Also, what keeps all the fuel from burning in the prechamber? Is it a lack of oxygen because very little air is allowed to enter the prechamber during compression? That would be very dirty as the flame would smother out causing lots of CO. I also have an issue with the idea that the main quantity of fuel is blown into the cylinder to ignite and burn, would that not tend to nail like mad, (like a DI engine), as there would be a large amount of fuel ignited, vrs the fuel igniting as it is injected?
And another thing, if the combustion chamber is in the cylinder, and not the prechamber, how does the prechamber have any affect the ability of the engine to rev faster than a DI engine?
Statement (A) of theory #1
The cylinder pressure is always higher than the prechamber pressure, (pre-injection), because of the small holes restricting air flow into the prechamber. Fuel is dispersed from the prechamber and throughout the cylinder to be burnt, by a pressure differential created by a small amount of fuel that is burnt in the prechamber, which raises the prechamber pressure above the cylinder pressure, causing gasses to flow from the prechamber to the cylinder.
Thought pertaining to Statement (A) of theory #1;
If, per theory #1, the majority of fuel is burnt in the cylinder, then the pressure in the cylinder will quickly become higher than the pressure in the prechamber when the fuel ignites. This pressure differential would cause flow from the cylinder into the prechamber.
If there is only enough air in the prechamber to support the initial combustion of the small amount of fuel that propelled the fuel into the cylinder to begin with, then unless all the fuel has made it into the cylinder before it ignites, any fuel that is flowing out of the prechamber will be pushed back into the prechamber in an effort to balance the higher cylinder and lower prechamber pressures, and any flame would be smothered out once it entered the prechamber, then expelled back into the cylinder once the cylinder pressure drops bellow the prechamber pressure. This would produce lots of partially brunt fuel, CO, not a good emission.
Even if the fuel gradually ignited as it leaves the prehamber, the moment the cylinder pressure is equal to, or higher than, the prehamber pressure, the fuel will stop flowing from the prechamber to the cylinder, and the fire will go out because there is not enough air in the prechamber to sustain combustion.
Because the air in the prechamber was used up during the initial push, another burst of pressure from combustion in the prehchamber can not be possible unless additional air from the cylinder is forced into the prechamber, allowing another burst that will push a second wave of fuel into the cylinder until the pressures switch again. This would cause multiple ignitions in the cylinder as the main portion of the fuel would be expelled from the prechamber in pulses, as the cylinder and prechamber trade high and low pressure states
Keeping in mind that the start of injection takes place before TDC, and therefore the cylinder pressure is continually rising from compression, before and during, the duration of the injection. With out a continuously higher pressure in the prechamber than the cylinder, a sustained dispersion of fuel into the constantly increasing pressures of the cylinder is not possible, as flow is from high pressure to low pressure.
Unless the prechamber pressure is constantly increasing, maintaining a higher pressure than the cylinder pressure throughout the entire injection and combustion cycle, then I do not see how a continuous flame front can be maintained in the cylinder.
Additionally, there seems to be a consensus that the prechambers ability to maintain a high pressure longer than the cylinder, allows the IDI engine to rev higher than a DI engine. If that is the case, and the majority of the fuel is burned in the cylinder and not the prechamber, then how does the pressure in the prechamber, (that does not contain any burning fuel because the little amount of air that was allowed to enter the prechamber was used up during the pulse sequence of the injection), have anything to do with the combustion environment in the cylinder? Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?
01-27-2011, 09:03 PM
#76
It would seem that the pre chamber controls the burn rate in a way that would allow higher compression, without damaging pressure spikes.
Do we know if an IDI engine is capable of higher speed because of the pre chamber or the higher compression?
I don't have to much time to think about this tonight. But a few comments. IDI engines always have higher compression. Cummins is about 17:1, Mercedes about 21:1. Perhaps to get the pressure higher in the pre chamber? It would seem to me that, when the piston is in the compression stroke the pre chamber may well be at a lower compression, at running speed. What would happen to the Cummins if the compression where raised to the same as the Mercedes?
It would seem that the pre chamber controls the burn rate in a way that would allow higher compression, without damaging pressure spikes.
Do we know if an IDI engine is capable of higher speed because of the pre chamber or the higher compression?
01-27-2011, 09:05 PM
#77
Combustion does happen in pre cup and pressure front propagates out into cylinder. But at any time in any space pressure is the same.
1977 300D for parts? Just a pile of rust but still runs!
1984 190D 2.2 - gone to better home
1987 Dodge Maxivan with OM603 and Goran’s 7.5 backroads terror
1987 300TD - tinker toy
1989 300TE - parts
1991 300TE - backyards decor
1991 300TD - Barrote’s 7.5
1992 300TD - semi-STD(Goran modified 7.5 ip but still with factory turbo+at)
1998 E300TD - dd with DSL1 now
1998 ML320 - snow ride
2014 Sprinter 2500 - Malone’s tune + pedal box
In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.
Combustion does happen in pre cup and pressure front propagates out into cylinder. But at any time in any space pressure is the same.
1977 300D for parts? Just a pile of rust but still runs!
1984 190D 2.2 - gone to better home
1987 Dodge Maxivan with OM603 and Goran’s 7.5 backroads terror
1987 300TD - tinker toy
1989 300TE - parts
1991 300TE - backyards decor
1991 300TD - Barrote’s 7.5
1992 300TD - semi-STD(Goran modified 7.5 ip but still with factory turbo+at)
1998 E300TD - dd with DSL1 now
1998 ML320 - snow ride
2014 Sprinter 2500 - Malone’s tune + pedal box
01-27-2011, 11:36 PM
#78
(01-27-2011, 09:05 PM)anjay In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.
Combustion does happen in pre cup and pressure front propagates out into cylinder. But at any time in any space pressure is the same.
Is it safe to say you lean toward #2? I'm trying to drum up support, as I like #2 my self. I am putting together some thoughts regarding #2.
Regarding the pressure. If this were a filled hydraulic system I would agree with you, however, in this case, the gasses that fill both environments, (cylinder and prechamber), are very compressible. Because the cylinder and prechamber are connected by small orifices, if the cylinder sees a very rapid change in pressure, would the speed at which the other side equalizes pressure not be determined, or regulated by the bleed rate of the orifices?
(01-27-2011, 09:05 PM)anjay In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.
Combustion does happen in pre cup and pressure front propagates out into cylinder. But at any time in any space pressure is the same.
Is it safe to say you lean toward #2? I'm trying to drum up support, as I like #2 my self. I am putting together some thoughts regarding #2.
Regarding the pressure. If this were a filled hydraulic system I would agree with you, however, in this case, the gasses that fill both environments, (cylinder and prechamber), are very compressible. Because the cylinder and prechamber are connected by small orifices, if the cylinder sees a very rapid change in pressure, would the speed at which the other side equalizes pressure not be determined, or regulated by the bleed rate of the orifices?
01-28-2011, 12:19 AM
#79
With stock fueling your making x amount of pressure compared to y amount of flow through the holes.
With increased fueling your increasing your pressure but not increasing the size of the holes you will get more flow to a point but your pressure differential will be greater.
I'm seeing that as lost power to a point.
That's looking at it if all combustion occurs in the precup or starts in the precup.
Either the fuel or the air from combustion has to go through those holes. If you increase your fueling and essentially raising your volumetric efficiency I don't see why enlarging the holes a percentage of the percent that you are raising your volumetric efficiency.
-Jesse
80 300sd hy35, front mount intercooler, w115 intake, rack limiter removed, Alda removed, full load turned up, boost, ebp, trans, pyro, egr delete, 3.5" exhaust, e-fan, 16x8 rims with, 245/50 tires, lowered, bilstien 5100's, 12" front brakes, 2.65:1 diff.
97 f250 psd 4x4, crawler
70 f250 390
83 Volvo 242, lots of mods
66 Volvo amazon
10 mistsubishi fuso service truck.
Take any flowing fluid/ gas push it through a orifice and you "will" have 2 different pressures. Increase that orifice size and your pressure differential "will" be less severe make the orifice smaller and that pressure differential increases.
With stock fueling your making x amount of pressure compared to y amount of flow through the holes.
With increased fueling your increasing your pressure but not increasing the size of the holes you will get more flow to a point but your pressure differential will be greater.
I'm seeing that as lost power to a point.
That's looking at it if all combustion occurs in the precup or starts in the precup.
Either the fuel or the air from combustion has to go through those holes. If you increase your fueling and essentially raising your volumetric efficiency I don't see why enlarging the holes a percentage of the percent that you are raising your volumetric efficiency.
-Jesse
80 300sd hy35, front mount intercooler, w115 intake, rack limiter removed, Alda removed, full load turned up, boost, ebp, trans, pyro, egr delete, 3.5" exhaust, e-fan, 16x8 rims with, 245/50 tires, lowered, bilstien 5100's, 12" front brakes, 2.65:1 diff.
97 f250 psd 4x4, crawler
70 f250 390
83 Volvo 242, lots of mods
66 Volvo amazon
10 mistsubishi fuso service truck.
01-28-2011, 12:23 AM
#80
--------------------------------------------------------------------------------
um... can you proof read that and re-type it?
Either the fuel or the air from combustion has to go through those holes. If you increase your fueling and essentially raising your volumetric efficiency I don't see why enlarging the holes a percentage of the percent that you are raising your volumetric efficiency.
--------------------------------------------------------------------------------
um... can you proof read that and re-type it?
01-28-2011, 12:24 AM
#81
(01-27-2011, 05:39 PM)ForcedInduction(01-27-2011, 05:03 PM)Captain America Smoking is only good when you have the ponies to back it up!Smoke is never good. Anything more than a slight haze is power dumped out the tailpipe.
Joke dude. It was a joke.
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-28-2011, 12:24 AM #81(01-27-2011, 05:39 PM)ForcedInduction(01-27-2011, 05:03 PM)Captain America Smoking is only good when you have the ponies to back it up!Smoke is never good. Anything more than a slight haze is power dumped out the tailpipe.
Joke dude. It was a joke.
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-28-2011, 01:10 AM
#83
What about Soviet Russia?
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-28-2011, 01:10 AM #83Oops, I forgot
What about Soviet Russia?
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-28-2011, 07:02 AM
#85
(01-27-2011, 07:16 PM)DeliveryValve How can 135 bar injected fuel can create this so called turbulence.It doesn't, thats what the ball inside the prechamber is for. The ball disturbs airflow coming into the prechamber and aids in atomizing the fuel (like spraying a pressure washer at a wall). If you've ever looked at the spray pattern from our injectors its pretty much a straight point, unlike the fine mist of most injectors, and its what sets our IDI system apart from others such as VW as anjay pointed out...
Quote:In passanger cars pre cup engines are used do to it more quite operation.
(01-27-2011, 07:45 PM)OM616 Given that #1 is getting the most votesThere is nothing to "vote" on, people's opinions won't change the physical operation of the engines.
Quote:It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.Correct, that is how precombustion chamber diesels operate.
Quote:For example, if only a very small portion of air is allowed to enter the prechamber, then the prechamber pressure will be lower than the cylinder pressure, and the less air that can get into the prechamber, the grater the pressure differential.You're missing combustion. Compression is only one of the cycles.
Quote:wouldn’t all the fuel need to be injected into the prechamber before a small portion of it is ignited?http://hubpages.com/hub/Combustion-in-Diesel-Engines
Ignition delay period is the time span between commencement of injection and the start of ignition.
* The fuel emerges into the cylinder as small liquid particles, which are surrounded by hot compressed air.
* They receive heat from the air and more volatile constituents of the fuel vaporise.
* During the ignition delay period a large part of the fuel charge is prepared for combustion.
* During the ignition delay, the injector continued to inject the fuel and, if this has built up a sufficient quantity, the rapid combustion and pressure rise will be quite violent, causing detonation and shock loading creating a noise termed diesel knock.
Quote:First, what ignites the fuel, or more correctly stated, what prevents the fuel from igniting in the prechamber, until after all the fuel is injected into the prechamber?First; the ball in the prechamber aids in ignition. In operation the ball is glowing hot from the combustion, thats why glowplugs are required to start these engines cold when most DI engines don't even have glowplugs (they can ignite from compression heat alone). To the second part, see ignition delay above.
Quote:Also, what keeps all the fuel from burning in the prechamber?At idle and low power, nothing. The injected quantity is plenty small to burn completely even in the limited air volume.
At higher loads its the restricted volume of air prevents complete combustion and is what pretreats/vaporizes the fuel to allow high-speed power. Thats why we can make power 3000-5500+rpm when most DI diesels fall on their face above 3000rpm.
Quote:And another thing, if the combustion chamber is in the cylinder, and not the prechamber, how does the prechamber have any affect the ability of the engine to rev faster than a DI engine?See above. Modern common rail engines are catching up because the common rail design allows multiple injections per cycle, which allows the computer to superheat the compression air (pre-injection) so the main injection burns smoother and faster.
Quote:Statement (A) of fact #1
Quote:Additionally, there seems to be a consensus that the prechambers ability to maintain a high pressure longer than the cylinder, allows the IDI engine to rev higher than a DI engine. If that is the case, and the majority of the fuel is burned in the cylinder and not the prechamber, then how does the pressure in the prechamber, ... have anything to do with the combustion environment in the cylinder?It doesn't. The prechamber is still pressurized by the initial combustion, and being restricted by the orifice, the pressure inside will be higher than the cylinder pressure for most of the power stroke.
Quote:Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?For old DI engines, no. The fuel in an idi engine is much better atomized and heated.
For modern CR DI engines, they're pretty close, but not quite there yet.
(01-27-2011, 09:03 PM)ronnie Perhaps to get the pressure higher in the pre chamber?Half. It must make up for the restriction in the prechamber, but the conditioning of the fuel allows the higher compression because it burns smoother.
Quote:What would happen to the Cummins if the compression where raised to the same as the Mercedes?Higher efficiency. There are a few competition pullers running high compression, there was recently one in Diesel Power Mag running 21:1.
Quote:Do we know if an IDI engine is capable of higher speed because of the pre chamber or the higher compression?Neither directly. There are plenty of competition DI engines revving past 5000rpm.
Quote:In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.Thats not what Dalton's Law is, and it only works for ideal gases.
Quote:I'm trying to drum up supportDenial doesn't alter fact.
Quote:Maybe he still believes in soviet russia thats why he is always so angry?Mother Russia never died.
This post was last modified: 01-28-2011, 07:17 AM by ForcedInduction.
ForcedInduction
01-28-2011, 07:02 AM
#85
(01-27-2011, 07:16 PM)DeliveryValve How can 135 bar injected fuel can create this so called turbulence.It doesn't, thats what the ball inside the prechamber is for. The ball disturbs airflow coming into the prechamber and aids in atomizing the fuel (like spraying a pressure washer at a wall). If you've ever looked at the spray pattern from our injectors its pretty much a straight point, unlike the fine mist of most injectors, and its what sets our IDI system apart from others such as VW as anjay pointed out...
Quote:In passanger cars pre cup engines are used do to it more quite operation.
(01-27-2011, 07:45 PM)OM616 Given that #1 is getting the most votesThere is nothing to "vote" on, people's opinions won't change the physical operation of the engines.
Quote:It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.Correct, that is how precombustion chamber diesels operate.
Quote:For example, if only a very small portion of air is allowed to enter the prechamber, then the prechamber pressure will be lower than the cylinder pressure, and the less air that can get into the prechamber, the grater the pressure differential.You're missing combustion. Compression is only one of the cycles.
Quote:wouldn’t all the fuel need to be injected into the prechamber before a small portion of it is ignited?http://hubpages.com/hub/Combustion-in-Diesel-Engines
Ignition delay period is the time span between commencement of injection and the start of ignition.
* The fuel emerges into the cylinder as small liquid particles, which are surrounded by hot compressed air.
* They receive heat from the air and more volatile constituents of the fuel vaporise.
* During the ignition delay period a large part of the fuel charge is prepared for combustion.
* During the ignition delay, the injector continued to inject the fuel and, if this has built up a sufficient quantity, the rapid combustion and pressure rise will be quite violent, causing detonation and shock loading creating a noise termed diesel knock.
Quote:First, what ignites the fuel, or more correctly stated, what prevents the fuel from igniting in the prechamber, until after all the fuel is injected into the prechamber?First; the ball in the prechamber aids in ignition. In operation the ball is glowing hot from the combustion, thats why glowplugs are required to start these engines cold when most DI engines don't even have glowplugs (they can ignite from compression heat alone). To the second part, see ignition delay above.
Quote:Also, what keeps all the fuel from burning in the prechamber?At idle and low power, nothing. The injected quantity is plenty small to burn completely even in the limited air volume.
At higher loads its the restricted volume of air prevents complete combustion and is what pretreats/vaporizes the fuel to allow high-speed power. Thats why we can make power 3000-5500+rpm when most DI diesels fall on their face above 3000rpm.
Quote:And another thing, if the combustion chamber is in the cylinder, and not the prechamber, how does the prechamber have any affect the ability of the engine to rev faster than a DI engine?See above. Modern common rail engines are catching up because the common rail design allows multiple injections per cycle, which allows the computer to superheat the compression air (pre-injection) so the main injection burns smoother and faster.
Quote:Statement (A) of fact #1
Quote:Additionally, there seems to be a consensus that the prechambers ability to maintain a high pressure longer than the cylinder, allows the IDI engine to rev higher than a DI engine. If that is the case, and the majority of the fuel is burned in the cylinder and not the prechamber, then how does the pressure in the prechamber, ... have anything to do with the combustion environment in the cylinder?It doesn't. The prechamber is still pressurized by the initial combustion, and being restricted by the orifice, the pressure inside will be higher than the cylinder pressure for most of the power stroke.
Quote:Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?For old DI engines, no. The fuel in an idi engine is much better atomized and heated.
For modern CR DI engines, they're pretty close, but not quite there yet.
(01-27-2011, 09:03 PM)ronnie Perhaps to get the pressure higher in the pre chamber?Half. It must make up for the restriction in the prechamber, but the conditioning of the fuel allows the higher compression because it burns smoother.
Quote:What would happen to the Cummins if the compression where raised to the same as the Mercedes?Higher efficiency. There are a few competition pullers running high compression, there was recently one in Diesel Power Mag running 21:1.
Quote:Do we know if an IDI engine is capable of higher speed because of the pre chamber or the higher compression?Neither directly. There are plenty of competition DI engines revving past 5000rpm.
Quote:In closed system (space) in any location pressure is the same. Dalton's Law of partial pressures.Thats not what Dalton's Law is, and it only works for ideal gases.
Quote:I'm trying to drum up supportDenial doesn't alter fact.
Quote:Maybe he still believes in soviet russia thats why he is always so angry?Mother Russia never died.
01-28-2011, 08:46 AM
#86
(01-28-2011, 07:02 AM)ForcedInduction(01-27-2011, 07:16 PM)DeliveryValve How can 135 bar injected fuel can create this so called turbulence.It doesn't, thats what the ball inside the prechamber is for. The ball disturbs airflow coming into the prechamber and aids in atomizing the fuel (like spraying a pressure washer at a wall). If you've ever looked at the spray pattern from our injectors its pretty much a straight point, unlike the fine mist of most injectors, and its what sets our IDI system apart from others such as VW as anjay pointed out...
Quote:In passanger cars pre cup engines are used do to it more quite operation....
Quote:It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.Correct, that is how precombustion chamber diesels operate.
.
That is what I trying to get at in my previous question in terms of a small portion of fuel getting ignited in the prechamber I was confused to the different scenarios that was posted, hence my question. Regarding turbulence, yes ball in the prechamber operates that way. But the ignition that follows causes the turbulence out of the prechamber and into the combustion chamber.
Gota love Mercedes Diesels!
.
DeliveryValve
01-28-2011, 08:46 AM #86(01-28-2011, 07:02 AM)ForcedInduction(01-27-2011, 07:16 PM)DeliveryValve How can 135 bar injected fuel can create this so called turbulence.It doesn't, thats what the ball inside the prechamber is for. The ball disturbs airflow coming into the prechamber and aids in atomizing the fuel (like spraying a pressure washer at a wall). If you've ever looked at the spray pattern from our injectors its pretty much a straight point, unlike the fine mist of most injectors, and its what sets our IDI system apart from others such as VW as anjay pointed out...
Quote:In passanger cars pre cup engines are used do to it more quite operation....
Quote:It has been suggested that a very small portion of the fuel that is injected ignites in the prechamber, creating heat that will preheat the remaining injected fuel, that is not ignited, and pressurize the prechamber causing the heated fuel fog to be expelled from the burn holes.Correct, that is how precombustion chamber diesels operate.
.
That is what I trying to get at in my previous question in terms of a small portion of fuel getting ignited in the prechamber I was confused to the different scenarios that was posted, hence my question. Regarding turbulence, yes ball in the prechamber operates that way. But the ignition that follows causes the turbulence out of the prechamber and into the combustion chamber.
Gota love Mercedes Diesels!
.
01-28-2011, 08:58 AM
#87
" It is far easier to get forgiveness rather than permission"
Riverstick
01-28-2011, 08:58 AM #87Very informative thread.....various theories but I think they have been ironed out and funnelled into a few common thoughts....One thing i do recall is that the diesel shops in the Netherlands several years ago used to replace the cross pin in the swirl chamber to improve output on the naturally aspirated engines. This had the effect of increasing the compression ratio within the precombustion chamber itself and apparently gave the engine more power. They also used to raise the breaking pressure of the injectors and advance the timing to compensate for this. Their naturally aspirated mercs used to perform fantastic afterwards.....
" It is far easier to get forgiveness rather than permission"
01-28-2011, 01:06 PM
#88
Keep in mind that this discussion is about producing more power, not a quieter operation. I agree that smaller holes = quieter operation, I am interested in more power. From my perspective, to get more power, more fuel will need to be burnt in the prechamber, and the expanding gasses will need to be able to escape faster as well. Fortunately both are aided from increasing the hole diameter.
If the size of the holes were increased to allow more air into the prechamber, the prechamber air temperature, (before, and at the time of injection), would be higher from the additional pressure, (increasing the conditioning of the fuel), aiding in combustion.
Also, if more air is allowed to enter the prechamber, then the pressure differential during compression would be lower, if the prechamber pressure is always higher than the cylinder pressure during combustion with the small holes, (high pressure differential during compression), then with a lower compression pressure differential, the prechamber combustion pressure would be even higher than the cylinder pressure, blowing out its contents even faster and with more vigor.
The faster the engine is running the less time there is for air to make it into the prechamber, lowering the prechamber pressure and reducing the amount of vigor. Less vigor, bad, more vigor, good.
If more air is allowed to flow into the prechamber then the swirl in the prechamber will be increased, again more vigorous, and the fuel/air mixture conditioning would be improved, resulting in a more vigorous combustion. (more power)
If larger elements are used, then the length of time that the fuel is injected in is reduced, and the holes will need to flow at an increased rate to keep up. With small holes the restriction would reduce efficiency as the holes would hold up the works.
Any extra air that is allowed to enter the prechamber, and is not used up, will be expelled, if the holes will flow enough that is, and the pressure will push on the piston.
The closer the prechamber and cylinder pressures are during compression, the less energy that is used to raise the prechamber pressure above the cylinder pressure during combustion. (poorly worded I know, but I hope everyone gets my point).
All in all, I see larger holes as a win win. And the reports, from other members besides me, support larger holes.
I think that ¼ to 2/3 (or more) of the fuel should be burnt in the prechamber, and the wrest in the cylinder in a two part process. The difference in my thinking is that the holes be very large to allow a large amount of air to flow in and out of the prechamber, raising the compressed air temperature in the prechamber, and reaching ignition temperatures sooner, allowing for advanced injection timing.
The increased air entering the prechamber will create a stronger swirl improving the mix of gasses and fuel. Due to the lower cylinder / prechamber pressure differential, the result of larger holes, more pressure will be exerted on the piston sooner, and a grater amount of pressure will be used to push on the piston, instead of being needed to maintain a higher prechamber pressure because of the high cylinder / prechamber pressure differential.
Got to go.
This post was last modified: 01-28-2011, 04:19 PM by OM616.
The link is describing a DI diesel operation. I didn't see any references to a prechamber affects / function anywhere. The entire reason for the prechamber is to change the combustion process buy braking it up into smaller processes that better refine the total combustion, resulting in a “quieter” operation instead of "diesel knock."
Keep in mind that this discussion is about producing more power, not a quieter operation. I agree that smaller holes = quieter operation, I am interested in more power. From my perspective, to get more power, more fuel will need to be burnt in the prechamber, and the expanding gasses will need to be able to escape faster as well. Fortunately both are aided from increasing the hole diameter.
If the size of the holes were increased to allow more air into the prechamber, the prechamber air temperature, (before, and at the time of injection), would be higher from the additional pressure, (increasing the conditioning of the fuel), aiding in combustion.
Also, if more air is allowed to enter the prechamber, then the pressure differential during compression would be lower, if the prechamber pressure is always higher than the cylinder pressure during combustion with the small holes, (high pressure differential during compression), then with a lower compression pressure differential, the prechamber combustion pressure would be even higher than the cylinder pressure, blowing out its contents even faster and with more vigor.
The faster the engine is running the less time there is for air to make it into the prechamber, lowering the prechamber pressure and reducing the amount of vigor. Less vigor, bad, more vigor, good.
If more air is allowed to flow into the prechamber then the swirl in the prechamber will be increased, again more vigorous, and the fuel/air mixture conditioning would be improved, resulting in a more vigorous combustion. (more power)
If larger elements are used, then the length of time that the fuel is injected in is reduced, and the holes will need to flow at an increased rate to keep up. With small holes the restriction would reduce efficiency as the holes would hold up the works.
Any extra air that is allowed to enter the prechamber, and is not used up, will be expelled, if the holes will flow enough that is, and the pressure will push on the piston.
The closer the prechamber and cylinder pressures are during compression, the less energy that is used to raise the prechamber pressure above the cylinder pressure during combustion. (poorly worded I know, but I hope everyone gets my point).
All in all, I see larger holes as a win win. And the reports, from other members besides me, support larger holes.
I think that ¼ to 2/3 (or more) of the fuel should be burnt in the prechamber, and the wrest in the cylinder in a two part process. The difference in my thinking is that the holes be very large to allow a large amount of air to flow in and out of the prechamber, raising the compressed air temperature in the prechamber, and reaching ignition temperatures sooner, allowing for advanced injection timing.
The increased air entering the prechamber will create a stronger swirl improving the mix of gasses and fuel. Due to the lower cylinder / prechamber pressure differential, the result of larger holes, more pressure will be exerted on the piston sooner, and a grater amount of pressure will be used to push on the piston, instead of being needed to maintain a higher prechamber pressure because of the high cylinder / prechamber pressure differential.
Got to go.
01-28-2011, 02:59 PM
#89
(01-28-2011, 07:02 AM)ForcedInduction See above. Modern common rail engines are catching up because the common rail design allows multiple injections per cycle, which allows the computer to superheat the compression air (pre-injection) so the main injection burns smoother and faster.
Quote:Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?For old DI engines, no. The fuel in an idi engine is much better atomized and heated.
For modern CR DI engines, they're pretty close, but not quite there yet.
concerning the atomization the common rail DI is better than IDI
Gruß
Volker
This post was last modified: 01-28-2011, 03:05 PM by Volker407.
(01-28-2011, 07:02 AM)ForcedInduction See above. Modern common rail engines are catching up because the common rail design allows multiple injections per cycle, which allows the computer to superheat the compression air (pre-injection) so the main injection burns smoother and faster.
Quote:Once the fuel is in the cylinder, the combustion environment in the cylinder is the same as in a DI engine isn’t it?For old DI engines, no. The fuel in an idi engine is much better atomized and heated.
For modern CR DI engines, they're pretty close, but not quite there yet.
concerning the atomization the common rail DI is better than IDI
Gruß
Volker
01-28-2011, 03:27 PM
#90
(01-28-2011, 08:58 AM)Riverstick Very informative thread.....various theories but I think they have been ironed out and funnelled into a few common thoughts
This thread is a real train wreck isn't it...LOL!! I love it!
Just saw that the rules were just updated, going to have a look.
Were good.
Although I can see this being seen as an attempt to cause trouble, I am honestly interested in his thoughts. This is actually a complement to the members who posted the posts that I would like him to comment on, and I hope this does not deter members from posting. I am truly interested in his thoughts as there are some points in the mentioned posts that have been apparently overlooked.
Mr. Induction. I am very interested in your thoughts on the following posts, #25, #36, #44, #66, #74, #79, #80. Please feel free to take up as much space as you feel you need to post your comments to each of the previously identified posts.
This is genuinely not a smart @$$ request.
This post was last modified: 01-28-2011, 03:57 PM by OM616.
(01-28-2011, 08:58 AM)Riverstick Very informative thread.....various theories but I think they have been ironed out and funnelled into a few common thoughts
This thread is a real train wreck isn't it...LOL!! I love it!
Just saw that the rules were just updated, going to have a look.
Were good.
Although I can see this being seen as an attempt to cause trouble, I am honestly interested in his thoughts. This is actually a complement to the members who posted the posts that I would like him to comment on, and I hope this does not deter members from posting. I am truly interested in his thoughts as there are some points in the mentioned posts that have been apparently overlooked.
Mr. Induction. I am very interested in your thoughts on the following posts, #25, #36, #44, #66, #74, #79, #80. Please feel free to take up as much space as you feel you need to post your comments to each of the previously identified posts.
This is genuinely not a smart @$$ request.
01-28-2011, 04:17 PM
#91
(01-28-2011, 08:58 AM)Riverstick .....They also used to raise the breaking pressure of the injectors and advance the timing to compensate for this. Their naturally aspirated mercs used to perform fantastic afterwards.....
This sounds plausible?
I think you've got to remember about the little pearly glowing ball in the Precup, OM616, I didnt see any mention of it in the last few posts. The GP initially gets everything all nice and toasty and then compression and combustion continues and maintains the heat. With the ball glowing hot + the compression + the small (somewhat) contained space is what sets it apart from the rest of the cylinder... and keeps the precup at a higher pressure than the rest of the cylinder for "...most of the power stroke." as Forced stated..
Correct me if I'm wrong
This post was last modified: 01-28-2011, 04:27 PM by Captain America.
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
Captain America
01-28-2011, 04:17 PM #91(01-28-2011, 08:58 AM)Riverstick .....They also used to raise the breaking pressure of the injectors and advance the timing to compensate for this. Their naturally aspirated mercs used to perform fantastic afterwards.....
This sounds plausible?
I think you've got to remember about the little pearly glowing ball in the Precup, OM616, I didnt see any mention of it in the last few posts. The GP initially gets everything all nice and toasty and then compression and combustion continues and maintains the heat. With the ball glowing hot + the compression + the small (somewhat) contained space is what sets it apart from the rest of the cylinder... and keeps the precup at a higher pressure than the rest of the cylinder for "...most of the power stroke." as Forced stated..
Correct me if I'm wrong
1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag
AX15 Jeep Trans swap in progress....
01-28-2011, 04:42 PM
#92
(01-28-2011, 04:17 PM)Captain America I think you've got to remember about the little pearly glowing ball in the Precup, OM616, I didnt see any mention of it in the last few posts. The GP initially gets everything all nice and toasty and then compression and combustion continues and maintains the heat. With the ball glowing hot + the compression + the small (somewhat) contained space is what sets it apart from the rest of the cylinder... and keeps the precup at a higher pressure than the rest of the cylinder for "...most of the power stroke." as Forced stated..
Correct me if I'm wrong.
No need.
I haven't forgotten about the pearly ball, (I like that).
I contend that more fuel actually burns in the prechamber than theory #1 indicates, quite a bit more.
(01-28-2011, 04:17 PM)Captain America I think you've got to remember about the little pearly glowing ball in the Precup, OM616, I didnt see any mention of it in the last few posts. The GP initially gets everything all nice and toasty and then compression and combustion continues and maintains the heat. With the ball glowing hot + the compression + the small (somewhat) contained space is what sets it apart from the rest of the cylinder... and keeps the precup at a higher pressure than the rest of the cylinder for "...most of the power stroke." as Forced stated..
Correct me if I'm wrong.
No need.
I haven't forgotten about the pearly ball, (I like that).
I contend that more fuel actually burns in the prechamber than theory #1 indicates, quite a bit more.
01-28-2011, 07:59 PM
#93
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?
I will join in and give my description of the prechamber operation(at full load).
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?
01-28-2011, 10:40 PM
#94
The bore of the 61X (per manual) is 3.58 in diameter, which has an area of 10.065968 sqin.
I have seen some piston to valve clearance measurements in the 2mm range, but for the sake of argument and simplicity lets say at TDC the distance from the head to the piston is .100 inches.
10.065968 X .100 = 1.0065968 cuin at TDC, (probably close with the .100 clearance because of the prechamber tip and prechamber pocket).
The 61X cylinder displacement is 36.036165 cuin
36.036165 divided by 1.0065968 = 35.79999999 to 1 compression ratio
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
40% of 1.7 cuin is .68 cuin
Although I have not cced a 61X prechamber, I would put its volume closer to 1 cuin. I'll try to cc one tomorrow.
Just to add to the excitement, some more numbers to consider. Not intended to support one idea or another, they are just numbers that might inspire a member to post.
The bore of the 61X (per manual) is 3.58 in diameter, which has an area of 10.065968 sqin.
I have seen some piston to valve clearance measurements in the 2mm range, but for the sake of argument and simplicity lets say at TDC the distance from the head to the piston is .100 inches.
10.065968 X .100 = 1.0065968 cuin at TDC, (probably close with the .100 clearance because of the prechamber tip and prechamber pocket).
The 61X cylinder displacement is 36.036165 cuin
36.036165 divided by 1.0065968 = 35.79999999 to 1 compression ratio
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
40% of 1.7 cuin is .68 cuin
Although I have not cced a 61X prechamber, I would put its volume closer to 1 cuin. I'll try to cc one tomorrow.
01-29-2011, 12:54 AM
#96
(01-26-2011, 07:33 PM)MTUPower I'll be headed to the yards here in Feb to pull a wagon head for modification. I need more power and less smoke in my wagon, and will be doing quite a bit in search of that goal. A VGT install is high on the list, but every little bit helps. With a spare head I can compare apples to apples with few other variables.
Get the 85yr. Turbo ones, Injector moved deeper ,better atomization,less smoking.
(01-28-2011, 07:59 PM)erling66 I will join in and give my description of the prechamber operation(at full load).Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?
This post was last modified: 01-29-2011, 01:11 AM by Hercules.
(01-26-2011, 07:33 PM)MTUPower I'll be headed to the yards here in Feb to pull a wagon head for modification. I need more power and less smoke in my wagon, and will be doing quite a bit in search of that goal. A VGT install is high on the list, but every little bit helps. With a spare head I can compare apples to apples with few other variables.
Get the 85yr. Turbo ones, Injector moved deeper ,better atomization,less smoking.
(01-28-2011, 07:59 PM)erling66 I will join in and give my description of the prechamber operation(at full load).Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?
01-29-2011, 02:26 AM
#97
The first step then might be to modify the holes to funnel like from "outside".
Can we learn more when we compare the N/A PC with turbo?
(larger bores, increased inner PC volume).
Tom
can we summarise that we want the air flow from compression into the PC with less restriction but reverse we want a "delay" for smooth combustion?
The first step then might be to modify the holes to funnel like from "outside".
Can we learn more when we compare the N/A PC with turbo?
(larger bores, increased inner PC volume).
Tom
01-29-2011, 05:56 AM
#98
(01-28-2011, 10:40 PM)OM616 Just to add to the excitement, some more numbers to consider. Not intended to support one idea or another, they are just numbers that might inspire a member to post.
The bore of the 61X (per manual) is 3.58 in diameter, which has an area of 10.065968 sqin.
I have seen some piston to valve clearance measurements in the 2mm range, but for the sake of argument and simplicity lets say at TDC the distance from the head to the piston is .100 inches.
10.065968 X .100 = 1.0065968 cuin at TDC, (probably close with the .100 clearance because of the prechamber tip and prechamber pocket).
The 61X cylinder displacement is 36.036165 cuin
36.036165 divided by 1.0065968 = 35.79999999 to 1 compression ratio
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
40% of 1.7 cuin is .68 cuin
Although I have not cced a 61X prechamber, I would put its volume closer to 1 cuin. I'll try to cc one tomorrow.
I guess your plan is to calculate how much air enters the PC in order to find out how much fuel/air mix is combusted inside the PC.
There are more details you need to take into your calculation.
Remember that the PC is not empty when the compression starts. There will be exhaust that has not escaped and there will be unburnt fuel.
Second, you will have to make calculation at ca20-24 degrees BTDC. The area in the combustion chamber is much larger at that time comparing to TDC. Why? that is probably the time the air flow stops to enter the PC because of the increased pressure caused by the atomized entering fuel.
Maybe it is only 10-15% of the air that is burnt inside the PC
(01-29-2011, 12:54 AM)Hercules Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The thermal load increased because of the increased pressure in the combustion chamber. Not a very desirable situation when you have already increased the pressure by more boost and extra fuel from the larger elements.
(01-29-2011, 02:26 AM)tomnik can we summarise that we want the air flow from compression into the PC with less restriction but reverse we want a "delay" for smooth combustion?
The first step then might be to modify the holes to funnel like from "outside".
Can we learn more when we compare the N/A PC with turbo?
(larger bores, increased inner PC volume).
Tom
Why would we want more air into the PC when we already have the sufficient amount(to perform the PCs task)? To move more of the combustion into the PC will only lead to less efficient engine(energy lost to heat in the PC)
Smooth combustion and better air/fuel mix and a complete combustion is nice to have:o) Mercedes did a pretty good job to create this with their PC
This post was last modified: 01-29-2011, 07:39 AM by erling66.
(01-28-2011, 10:40 PM)OM616 Just to add to the excitement, some more numbers to consider. Not intended to support one idea or another, they are just numbers that might inspire a member to post.
The bore of the 61X (per manual) is 3.58 in diameter, which has an area of 10.065968 sqin.
I have seen some piston to valve clearance measurements in the 2mm range, but for the sake of argument and simplicity lets say at TDC the distance from the head to the piston is .100 inches.
10.065968 X .100 = 1.0065968 cuin at TDC, (probably close with the .100 clearance because of the prechamber tip and prechamber pocket).
The 61X cylinder displacement is 36.036165 cuin
36.036165 divided by 1.0065968 = 35.79999999 to 1 compression ratio
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
40% of 1.7 cuin is .68 cuin
Although I have not cced a 61X prechamber, I would put its volume closer to 1 cuin. I'll try to cc one tomorrow.
I guess your plan is to calculate how much air enters the PC in order to find out how much fuel/air mix is combusted inside the PC.
There are more details you need to take into your calculation.
Remember that the PC is not empty when the compression starts. There will be exhaust that has not escaped and there will be unburnt fuel.
Second, you will have to make calculation at ca20-24 degrees BTDC. The area in the combustion chamber is much larger at that time comparing to TDC. Why? that is probably the time the air flow stops to enter the PC because of the increased pressure caused by the atomized entering fuel.
Maybe it is only 10-15% of the air that is burnt inside the PC
(01-29-2011, 12:54 AM)Hercules Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The thermal load increased because of the increased pressure in the combustion chamber. Not a very desirable situation when you have already increased the pressure by more boost and extra fuel from the larger elements.
(01-29-2011, 02:26 AM)tomnik can we summarise that we want the air flow from compression into the PC with less restriction but reverse we want a "delay" for smooth combustion?
The first step then might be to modify the holes to funnel like from "outside".
Can we learn more when we compare the N/A PC with turbo?
(larger bores, increased inner PC volume).
Tom
Why would we want more air into the PC when we already have the sufficient amount(to perform the PCs task)? To move more of the combustion into the PC will only lead to less efficient engine(energy lost to heat in the PC)
Smooth combustion and better air/fuel mix and a complete combustion is nice to have:o) Mercedes did a pretty good job to create this with their PC
01-29-2011, 08:22 AM
#99
(01-28-2011, 01:06 PM)OM616 I agree that smaller holes = quieter operation, I am interested in more power.
Enlarging the holes will not do that.
Quote:If the size of the holes were increased to allow more air into the prechamber, the prechamber air temperature, (before, and at the time of injection), would be higher from the additional pressure, (increasing the conditioning of the fuel), aiding in combustion.Inside the prechamber, where the increased combustion pressure is completely wasted on immovable surfaces.
Quote:Also, if more air is allowed to enter the prechamber, then the pressure differential during compression would be lowerReducing the amount of fuel ejected into the cylinder.
Quote:blowing out its contents even faster and with more vigor.It would actually blow out slower with less fuel reaching the main combustion chamber. Larger orifice = lower velocity.
Quote:The faster the engine is running the less time there is for air to make it into the prechamber, lowering the prechamber pressure and reducing the amount of vigor. Less vigor, bad, more vigor, good.Nope. The less air in the prechamber the less fuel wasted burning inside a non-movable chamber.
Quote:If more air is allowed to flow into the prechamber then the swirl in the prechamber will be increasedNo. Swirl would be reduced, remember; Larger orifice = lower velocity.
Quote:If larger elements are used, then the length of time that the fuel is injected in is reduced, and the holes will need to flow at an increased rate to keep up.Also no. Injection time has no bearing on swirl or atomization. Fuel volume is what necessitates larger orifices.
Quote:any extra air that is allowed to enter the prechamber, and is not used up, will be expelledSuch a condition would defeat the entire purpose of a prechamber. There is never leftover air in the prechamber (except possibly at idle).
Quote:The closer the prechamber and cylinder pressures are during compression, the less energy that is used to raise the prechamber pressure above the cylinder pressure during combustion.Incorrect. More energy would be wasted pushing on solid walls.
Quote:All in all, I see larger holes as a win win.If you're making over 100hp/cyl.
Quote:And the reports, from other members besides me, support larger holes.Except the ones that do it correctly are making 100hp/L on top of what any OM61x has ever achieved. Even the "245hp" Norwegian 240D doesn't meet the need for modifying the prechambers.
Quote:The increased air entering the prechamber will create a stronger swirl improving the mix of gasses and fuel.Incorrect. The air will be higher density and lower velocity, which will both work to reduce swirl.
Quote:Due to the lower cylinder / prechamber pressure differential, the result ofCorrected.
larger holes, more pressure will be wasted inside the prechamber
(01-28-2011, 02:59 PM)Volker407 concerning the atomization the common rail DI is better than IDINot for those up to the current generation. Current pressures are still too low to vaporize fuel to the extent a prechamber can.
They haven't even caught up to the pressures generated by early-90's unit injection systems. Thats why VW went with unit injectors (pumpe duse) in the previous generation of TDI. The primary reason for common rail today is unit injectors can't have multiple injection events beyond the compression/power strokes. Which is why manufacturers that have stayed with unit injectors, like Cat, use a "7th injector" post-turbo to produce the heat needed for DPF regeneration.
(01-28-2011, 10:40 PM)OM616 they are just numbers that might inspire a member to post.Your math is significantly off because you forgot to include headgasket thickness.
...
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
Quote:Get the 85yr. Turbo ones, Injector moved deeper ,better atomization,less smoking.There were no changes to 85 core engine. All changes were to bolt-on equipment (turbo, emissions system, air filter). The only change to the injection system was the addition of a rack position sensor to the injection pump and possibly a change in the governor settings.
ForcedInduction
01-29-2011, 08:22 AM
#99
(01-28-2011, 01:06 PM)OM616 I agree that smaller holes = quieter operation, I am interested in more power.
Enlarging the holes will not do that.
Quote:If the size of the holes were increased to allow more air into the prechamber, the prechamber air temperature, (before, and at the time of injection), would be higher from the additional pressure, (increasing the conditioning of the fuel), aiding in combustion.Inside the prechamber, where the increased combustion pressure is completely wasted on immovable surfaces.
Quote:Also, if more air is allowed to enter the prechamber, then the pressure differential during compression would be lowerReducing the amount of fuel ejected into the cylinder.
Quote:blowing out its contents even faster and with more vigor.It would actually blow out slower with less fuel reaching the main combustion chamber. Larger orifice = lower velocity.
Quote:The faster the engine is running the less time there is for air to make it into the prechamber, lowering the prechamber pressure and reducing the amount of vigor. Less vigor, bad, more vigor, good.Nope. The less air in the prechamber the less fuel wasted burning inside a non-movable chamber.
Quote:If more air is allowed to flow into the prechamber then the swirl in the prechamber will be increasedNo. Swirl would be reduced, remember; Larger orifice = lower velocity.
Quote:If larger elements are used, then the length of time that the fuel is injected in is reduced, and the holes will need to flow at an increased rate to keep up.Also no. Injection time has no bearing on swirl or atomization. Fuel volume is what necessitates larger orifices.
Quote:any extra air that is allowed to enter the prechamber, and is not used up, will be expelledSuch a condition would defeat the entire purpose of a prechamber. There is never leftover air in the prechamber (except possibly at idle).
Quote:The closer the prechamber and cylinder pressures are during compression, the less energy that is used to raise the prechamber pressure above the cylinder pressure during combustion.Incorrect. More energy would be wasted pushing on solid walls.
Quote:All in all, I see larger holes as a win win.If you're making over 100hp/cyl.
Quote:And the reports, from other members besides me, support larger holes.Except the ones that do it correctly are making 100hp/L on top of what any OM61x has ever achieved. Even the "245hp" Norwegian 240D doesn't meet the need for modifying the prechambers.
Quote:The increased air entering the prechamber will create a stronger swirl improving the mix of gasses and fuel.Incorrect. The air will be higher density and lower velocity, which will both work to reduce swirl.
Quote:Due to the lower cylinder / prechamber pressure differential, the result ofCorrected.
larger holes, more pressure will be wasted inside the prechamber
(01-28-2011, 02:59 PM)Volker407 concerning the atomization the common rail DI is better than IDINot for those up to the current generation. Current pressures are still too low to vaporize fuel to the extent a prechamber can.
They haven't even caught up to the pressures generated by early-90's unit injection systems. Thats why VW went with unit injectors (pumpe duse) in the previous generation of TDI. The primary reason for common rail today is unit injectors can't have multiple injection events beyond the compression/power strokes. Which is why manufacturers that have stayed with unit injectors, like Cat, use a "7th injector" post-turbo to produce the heat needed for DPF regeneration.
(01-28-2011, 10:40 PM)OM616 they are just numbers that might inspire a member to post.Your math is significantly off because you forgot to include headgasket thickness.
...
In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.
Quote:Get the 85yr. Turbo ones, Injector moved deeper ,better atomization,less smoking.There were no changes to 85 core engine. All changes were to bolt-on equipment (turbo, emissions system, air filter). The only change to the injection system was the addition of a rack position sensor to the injection pump and possibly a change in the governor settings.
01-29-2011, 08:42 AM
#100
I agree with this ststement. But, I do believe that OM616 is planning on larger elements & it could benefit. Also, Hercules stated that on an otherwise stock engine, that chamfering the holes on the outside benefitted. That would say to me that it allows more air into the prechamber with more velocity & induces better mixing. I am still confused about all of this technical writing, but getting a grasp on it. Is there some form of combustion in the PC? I am sure that there is. With that red hot ball & the pressures encountered, there must be. Is it a small or large percentage of total combustion? I cannot answer that.
Could a heavily modded engine benefit from chamfered AND enlarged PC holes, common sense would say yes to me. In a carbeuretor, when you increase air volume, you need to change jets (as an example).
Ed
yankneck696
01-29-2011, 08:42 AM #100<<Also no. Injection time has no bearing on swirl or atomization. Fuel volume is what necessitates larger orifices.>>
I agree with this ststement. But, I do believe that OM616 is planning on larger elements & it could benefit. Also, Hercules stated that on an otherwise stock engine, that chamfering the holes on the outside benefitted. That would say to me that it allows more air into the prechamber with more velocity & induces better mixing. I am still confused about all of this technical writing, but getting a grasp on it. Is there some form of combustion in the PC? I am sure that there is. With that red hot ball & the pressures encountered, there must be. Is it a small or large percentage of total combustion? I cannot answer that.
Could a heavily modded engine benefit from chamfered AND enlarged PC holes, common sense would say yes to me. In a carbeuretor, when you increase air volume, you need to change jets (as an example).
Ed
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