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+--- Thread: prechambers mods? (/showthread.php?tid=5643)
prechambers mods? - Tito - 06-01-2014
Hey guys. I was brainstorming in my mind about modding the pre chambers. especially the outflow of the chambers. Entirely deleting the "bulb" or drill extra holes. I can imagine it improving gas flow, when you're at 3 bar and +5500 rpm it kinda looks like a restriction. I can also see it give to much "oempf" to the piston at once, giving them some serious "piston slap". I don't know how to describe it, or the English word but i mean when the piston goes upwards on the right side on the cilinder and bangs agains the left side when going down. I can already hear this on my engine and some STD on youtube. I mean that nailing sound.
So, whats the reason why it's restricted? Could there be any improvement? and would it harm the engine? I'm just curious...
RE: prechambers mods? - raysorenson - 06-01-2014
There is an extensive, but maybe not exhaustive discussion of this in the archives. Search it up, or maybe some kinder soul than i will link you to it.
The only possible explanation for the positive results seen with hogging out the prechamber holes is that thermodynamic efficiency is increased at high loads. There's lots of heat moved from the prechamber to the cooling system, which is waste. Direct injected engines don't have this heat sink problem, and they're more efficient. Hope this helps:-)
RE: prechambers mods? - MFSuper90 - 06-01-2014
Jeemu and several other engine builders have stated that making the holes bigger helps a lot. You can't cut the end off, it would eliminate the whole design behind an IDI. You can if you replace stock injectors with direct injection units, but that involves changing pistons and is a very complicated process.
Several members having modded prechambers with success. Captain America being one of them, I am going to do this mod in the near future
RE: prechambers mods? - led-panzer - 06-01-2014
Personally I've heard enough positive reviews on this that I'm going to try it. Maybe a ~20% enlargement of all holes.
MFSuper90, do you have prechamber removal tools?
RE: prechambers mods? - Tito - 06-02-2014
Intresting! I thought of it making the engine better. But the heat inefficiency seems kinda strange. Full load on a idi engine always makes more heat in my opinion. The combustion takes place in the head. And at full load with black smoke there's no air to isolate the heat. Making the engine run hotter. I thought giving the prechamber more flow it would direct the gasses to the cylinder, where there's more air for the isolation.
RE: prechambers mods? - Simpler=Better - 06-02-2014
CAPTAIN AMERICA GET IN HERE
http://www.superturbodiesel.com/std/Thread-Prechamber-Mod-Flame-Front
http://www.superturbodiesel.com/std/Thread-Captain-s-82-300D
RE: prechambers mods? - raysorenson - 06-02-2014
(06-02-2014, 05:53 AM)Tito Intresting! I thought of it making the engine better. But the heat inefficiency seems kinda strange. Full load on a idi engine always makes more heat in my opinion. The combustion takes place in the head. And at full load with black smoke there's no air to isolate the heat. Making the engine run hotter. I thought giving the prechamber more flow it would direct the gasses to the cylinder, where there's more air for the isolation.
SAE #790039 The lower efficiency of the indirect-injection diesel engine, with respect to the direct injection type, is due to additional heat transfer from the combustion chamber, gas pumping between chambers, later injection timing and a different burning rate schedule.
It stands to reason that, if you don't add air, you don't add fuel and there wasn't a lot of smoke before the prechamber mods, the only place the power is coming from is an increase in efficiency. Less heat from combustion is moving to the cooling system and is instead being used to push the piston down the bore.
RE: prechambers mods? - MFSuper90 - 06-03-2014
(06-01-2014, 08:16 PM)led-panzer MFSuper90, do you have prechamber removal tools?
Yup, I made a tool to remove them. I removed a set in a blown engine I had, worked pretty well.
RE: prechambers mods? - Tito - 06-03-2014
Well, i'm definably going to try this. Thinking about a 20~30% bigger holes. It's for a om606 which I want to push 500hp. Also going to flow the head one of these days. I'm curious about the result. However I think I never get to notice it since I've never driven the stock pre chambers.
Edit, How about drilling one hole straight down?
RE: prechambers mods? - led-panzer - 06-03-2014
(06-03-2014, 02:28 PM)MFSuper90(06-01-2014, 08:16 PM)led-panzer MFSuper90, do you have prechamber removal tools?
Yup, I made a tool to remove them. I removed a set in a blown engine I had, worked pretty well.
Hmmm... Maybe we can work out a rental deal
I'm going to take mine out of my 85.
RE: prechambers mods? - MFSuper90 - 06-03-2014
(06-03-2014, 03:49 PM)Tito Well, i'm definably going to try this. Thinking about a 20~30% bigger holes. It's for a om606 which I want to push 500hp. Also going to flow the head one of these days. I'm curious about the result. However I think I never get to notice it since I've never driven the stock pre chambers.
Edit, How about drilling one hole straight down?
I don't think id do that, the holes are patterned that way to spread the flame evenly over the piston, kind of like what the bowl does on a direct injection engine
And led, we can probably work something out
RE: prechambers mods? - sassparilla_kid - 06-03-2014
I'll summon the captain
RE: prechambers mods? - Captain America - 06-03-2014
3 front holes to .156" rear two and bottom to .125”
Stock (broken) 1985 prechamber on the left and big baller Simpler=Better ported chamber on the right
So I have turned the fuel up (torque capsule) a lot! And also an unknown amount.... My EGTs only max at about 900 so I have much moar room to go I think. Also I might add that I'm making 14-15 psi with my Garrett w/ 60 trim compressor. Inter cooler not yet operational and Injection timing max advanced (didn't check what it actually is)
My 300 rips, and my transmission is dying (like most I guess) haha. She will be getting a AX-15 when money permits. Back to the subject though, I have been running this setup since beginning of February and even though Mr. OM616 recommended not to drill the bottom hole, we did anyway haha. Just on the fact that we were going for broke, kinda. I didn't want to stay too safe and have to pull, drill, ream, deburr, twice. My OM617 runs flawlessly!!!! I've been to the desert where I've been up hills that $40,000 four wheel drives couldn't make. I've pulled an old broken down F150 10 miles to my shop that research shows weighs about 5000lbs with no issues. It amazes people haha. And it starts cold with a flick of the ignition switch after the glow plugs have been on for 5 seconds.
Edit: she does have a bit of a power band.... 3k RPM and above is where she makes the most horse power. Still makes torque from 2k and above. I've I climb a local hill, well over 7% grade! I can easily make full boost by 2300 rpm due to turbo, fuel, and pre chamber mods.
Feels to me that she is always hungry for fuel, where as before it couldn't breath, could move the air.
RE: prechambers mods? - baldur - 06-04-2014
Well consider this. At TDC, how much of the combustion chamber volume is inside the prechamber?
RE: prechambers mods? - Simpler=Better - 06-04-2014
(06-04-2014, 05:44 AM)baldur Well consider this. At TDC, how much of the combustion chamber volume is inside the prechamber?
Since the pistons in a 617 stick up above the deck, and the head is flat-most of the volume is in the prechamber. Makes sense that this would speed things up a bit.
Warning to anyone trying this-spend the money on nice reamers. They're hard as hell. Use lots of oil and go slow.
RE: prechambers mods? - sassparilla_kid - 06-04-2014
Were captain's new or just old ones cleaned up?
RE: prechambers mods? - Simpler=Better - 06-04-2014
(06-04-2014, 09:41 AM)sassparilla_kid Were captain's new or just old ones cleaned up?
Oldies, he did a great job cleaning them though
RE: prechambers mods? - MFSuper90 - 06-04-2014
(06-04-2014, 11:15 AM)Simpler=Better(06-04-2014, 09:41 AM)sassparilla_kid Were captain's new or just old ones cleaned up?
Oldies, he did a great job cleaning them though
So if I blast mine and clean them up, would you entertain the idea of reaming them like capt's? The only stipulation being I wouldn't want the bottom hole done.
And of course I would pay you for your time and effort.
I bought a reamer with the intentions of doing it myself, but bought a tapered one because I am an idiot. Seems more reasonable to pay someone than buy a tool that I will only use once
RE: prechambers mods? - Simpler=Better - 06-05-2014
(06-04-2014, 03:45 PM)MFSuper90(06-04-2014, 11:15 AM)Simpler=Better(06-04-2014, 09:41 AM)sassparilla_kid Were captain's new or just old ones cleaned up?
Oldies, he did a great job cleaning them though
So if I blast mine and clean them up, would you entertain the idea of reaming them like capt's? The only stipulation being I wouldn't want the bottom hole done.
And of course I would pay you for your time and effort.
I bought a reamer with the intentions of doing it myself, but bought a tapered one because I am an idiot. Seems more reasonable to pay someone than buy a tool that I will only use once
It's not too hard, just run the tapered reamer on a slow drill speed and keep it bathed on oil. Keeping the drill square to the hole is critical.
To maintain the same depth each time paint a mark on the reamer after you do the first one
RE: prechambers mods? - sassparilla_kid - 06-05-2014
Time to bust out the lathe!!! Lol
RE: prechambers mods? - MFSuper90 - 06-05-2014
(06-05-2014, 09:07 AM)sassparilla_kid Time to bust out the lathe!!! Lol
What are you going to do with the lathe?
RE: prechambers mods? - Duncansport - 06-05-2014
(06-05-2014, 09:23 AM)MFSuper90(06-05-2014, 09:07 AM)sassparilla_kid Time to bust out the lathe!!! Lol
What are you going to do with the lathe?
Tear your hand off while trying to rheam out the PC's clearly
RE: prechambers mods? - MFSuper90 - 06-05-2014
(06-05-2014, 09:29 AM)Duncansport(06-05-2014, 09:23 AM)MFSuper90(06-05-2014, 09:07 AM)sassparilla_kid Time to bust out the lathe!!! Lol
What are you going to do with the lathe?
Tear your hand off while trying to rheam out the PC's clearly
lmao, I was kind of thinking the same thing
RE: prechambers mods? - Simpler=Better - 06-05-2014
Well, the hole diameter in the injector seat can be opened up as well so that part is done on a lathe. If you were good with a 4jaw and angle blocks I guess you could jig it up...would take 500 years though
EDIT: hole diameter in the injector seat, not burn tube. my bad.
RE: prechambers mods? - OM616 - 06-05-2014
(06-05-2014, 11:17 AM)Simpler=Better Well, the burn tube can be opened up as well so that part is done on a lathe.
I would not do that as I for see the thinner tube walls cracking and the burn tube breaking off.
The hole diameter in the injector seat however can be increased (where the injector nozzle sprays fuel). MB put out a bulletin a long time ago, one of the things that they recommended to do to reduce smoke was to increase the injector end hole diameter. They also said to lower the seat injector seat in the PC, but I forget the exact dimension, I got a little too frisky and cut my first ones too deep and the PC separated when I torque the injector.
The next time I do a PC, I am going to machine a slot across the three burn holes making a mouth so to speak.
RE: prechambers mods? - sassparilla_kid - 06-05-2014
Idk, I was barely awake. I forgot all the holes are on the sides lol
RE: prechambers mods? - Captain America - 06-06-2014
(06-05-2014, 12:05 PM)OM616(06-05-2014, 11:17 AM)Simpler=Better Well, the burn tube can be opened up as well so that part is done on a lathe.The next time I do a PC, I am going to machine a slot across the three burn holes making a mouth so to speak.
That is an interesting idea, sir. Like to see how that works out!
RE: prechambers mods? - barrote - 06-08-2014
hy there,
in my set up i will reopen the holes a bit, from 8 holes at 2,2 mm , i will have 8 X 2,5 mm, the botom one is 1,5mm and will stay the same for the moment. (606.04 pre cups). the pre cups marked 606.02 usually found in N/A engines are 8x2.1mm and botom hole at 1.3 or 1.4. , from this differnce one can understand that increasing fueling , involuntarly needs increasing the holes área or nr of holes etc.
taking acount the laws wich rule flow, increasing the holes beon the área of te neck hole will produce any significant gain, at least thats my bet. since the neck diameter is not more than 10mm (just guessing) i can´t see any gain using a hole wider than 2.50 , to 2,75 mm.
i´m trying the 2.5 mm .
let u know my findings.
any how, would be interesting to know if someone had opened the holes more than 2.5mm with positive results .
regards
RE: prechambers mods? - Tito - 06-09-2014
Thank you guys. Very useful info here. I'm letting you guys know how it will work out.
RE: prechambers mods? - Tito - 12-06-2014
So, I finaly started drilling them... It's the worst job ever.
First tried to drill with a 3mm hss drill bit. Took about an hour for one hole. Then found out could better use a grinded stone drill bit
![[Image: E4EE244E-B622-4E58-93DE-6EE8AA0143A1.jpg]](http://s1267.photobucket.com/user/Titotyfus/media/E4EE244E-B622-4E58-93DE-6EE8AA0143A1.jpg.html)
![[Image: BB0B0641-115F-4B15-B6CE-1F49C7DBEAAB.jpg]](http://s1267.photobucket.com/user/Titotyfus/media/BB0B0641-115F-4B15-B6CE-1F49C7DBEAAB.jpg.html)
If anyone is also trying this, rember to take out the glow plugs
![[Image: 6651335A-5FAD-4E83-88CB-7408883AE31D.jpg]](http://s1267.photobucket.com/user/Titotyfus/media/6651335A-5FAD-4E83-88CB-7408883AE31D.jpg.html)
Only problem I'm running into now is that everytime I get to the end of the hole, the drill bit grips and snaps off. So I'm drilling them till the last half mm or something and I'll need to find out how to drill the last bit.
RE: prechambers mods? - hooblah - 12-06-2014
Can you get your hands on a 3mm reamer?
And have you tried increasing the drill speed?
RE: prechambers mods? - Tito - 12-06-2014
Haven't tried both... Going to try a reamer
RE: prechambers mods? - EDH_Performance - 12-06-2014
Have you tried to heat them red hot, then drill them?
RE: prechambers mods? - barrote - 12-08-2014
HSS cr 0.7 drill bits , makes wonders . i use the brand BERNER germany . buy some 3 or 4. one lasts only one hole, then Sharp it do another one. in one hour is possible to drill all of them
.the best device is the electric screw driver( or the hell it is called in english) in high speed leave only 5mm of drill bit ouside, like that u can spare the bits.
i did 3 mm and 2mm at center. i did not tried them yet.
bonne chance.
PS: drill at dry conditions.
RE: prechambers mods? - hooblah - 12-08-2014
How about cobalt drill bits?
RE: prechambers mods? - swatmugga - 12-08-2014
Hey Tito
Why did you made the holes so big? I don't think that was a good idea. What were your thoughts?
You tripled the cross section of the holes!
RE: prechambers mods? - EDH_Performance - 12-08-2014
I think they are like butter to drill in, if you heat them up
All modified prechamber pictures from jeemu is red gloving
RE: prechambers mods? - barrote - 12-09-2014
(12-08-2014, 05:13 PM)hooblah How about cobalt drill bits?HSS Cr 0.7 , alias cobalt drill bits
RE: prechambers mods? - Tito - 12-09-2014
Cobalt drill bits... I guess they don't come from the diy store?
I used 5 stone drill bits, which where done after drilling 3 chambers, but mainly because the end gripped and only the tip is hardened. So it could pay off buying a cobalt drill bit. (12-08-2014, 05:59 PM)swatmugga Hey Tito
Why did you made the holes so big? I don't think that was a good idea. What were your thoughts?
You tripled the cross section of the holes!
The surface area hasn't even doubled. (2.2/2)^2*pi=3.8 and (3.0/2)^2*pi=7
Of course 7*8(number of holes)=56mm^2
I don't know the neck diameter... But guessing by the thickness of the wall it's indeed about 10mm. Giving a surface area of 78.5mm^2.
I didn't count the middle hole. So I should be good.
Furthermore I just trying. Maybe it doesn't work at all
anyone who knows the size Jeemu drilled? Heating the tip red hot is a problem because I only have a simple butane torch at work.
RE: prechambers mods? - barrote - 12-09-2014
hy there,
a pack of 10 x3mm HSS Cr 0.7 drill bits (those cobalt) maybe cost 15€ i dont think the issue is the cost. and amasing is that the drill bit u can Sharp. use again and again til the bit is over. i went through the same usually ending the hole is tricky thats why u shoul use a hand driller.
the inside hole is 6,7mm on the pre cups marked 606 02.
heating the PC wont do any good, what one could do is heating to where we can distemper the metal and after doing the holes heat treat them again for hardning . something is not so easy to do. simply cause we dont know the cokking temp.
regards
RE: prechambers mods? - Hercules - 12-10-2014
Colbalt drill bits work the best, flexible but still hard. Carbide too brittle for smaller holes. I usually use only one drill bit per hole, except the back holes ,hole too close to drilled size,must sharpen bits, small size bits brake easy. Do not need to heat prechambers, Have done eight sets . Using hand drill.
Hole size,exiting holes end of prechamber, 6% larger works best for me.Tryed 8% larger, performance fell off ,tryed 10% still less, engine less responsive. Test grounds , large mountain 6-8% grade, going from 7,000-9,000ft. Best performance,exiting hole area 2x transfer tube size. Injection nozzles,checked, cleaned ,set . Injection timing 26btc,valves checked, trying to be sure testing was accurate . What was less with larger holes,engine was less smooth,longer to respond to throttle,slower to pull grade. Hope this helps. What was my speed on this grade ,65mph in high gear with more on pedal,could still go faster. 82yr. 300sd,2.88 gears,16x265 tires.
RE: prechambers mods? - Simpler=Better - 12-10-2014
Captain disagrees:
![[Image: IMG_20140111_101408.jpg]](http://i64.photobucket.com/albums/h183/foxcrf450rider/Mobile%20Uploads/IMG_20140111_101408.jpg)
RE: prechambers mods? - Tito - 12-11-2014
That looks awesome
Time for some cobalt drill bits. I'll just order them online somewhere.
RE: prechambers mods? - sassparilla_kid - 12-11-2014
What are the stock hole sizes? And Simpler I think Hercules is saying +6%> +8%> +10%> stock in terms of performance
RE: prechambers mods? - raidaru - 12-12-2014
if u don't make a dyno/EGT test before/after PC mode, people will never know if it's really worth the headache drilling the PC's...............
RE: prechambers mods? - Tito - 12-12-2014
True, true....
I can use the dyno at my job. I'm actually also curious. Switching prechambers is easy. Take off the valve cover, remove injectors an glow plugs and I can just pull them out. If I'll find stock prechambers somehow...
RE: prechambers mods? - DiseaselWeasel - 12-12-2014
Next step: direct injection.
RE: prechambers mods? - Duncansport - 12-12-2014
(12-12-2014, 10:50 AM)DiseaselWeasel Next step: direct injection.
+1 on this
RE: prechambers mods? - barrote - 12-12-2014
yep ,
i thought about the same, thing is where to find a VE 5 full mechanichal. or lucas i belive.
injectors are piece of cake.
in europe the w210 E290 comes with a 602 DI lucas electrical pump.
if i could lay my hands on a VE5 mechanical with a MB flange ..... i´m dreaming boys
regards
ps: i have my pre cups ready , just missing the special tool to remove them.
RE: prechambers mods? - Tito - 12-13-2014
(12-12-2014, 03:32 PM)barrote yep ,
i thought about the same, thing is where to find a VE 5 full mechanichal. or lucas i belive.
injectors are piece of cake.
in europe the w210 E290 comes with a 602 DI lucas electrical pump.
if i could lay my hands on a VE5 mechanical with a MB flange ..... i´m dreaming boys
regards
ps: i have my pre cups ready , just missing the special tool to remove them.
You can buy the socket from eBay. Costed me 21 euros. You make make a chamber puller yourself like I did. Either with a screw type puller or a sliding hammer. I used a Volkswagen chain tensioner to make the tool. Same tread as the injector.
Btw I finished the job today. A cobalt drill bit works nicely