HIgher RPM for more power?
HIgher RPM for more power?
Hi,
As far as I know in our diesels om617/602/603 the IP sturts cutting fuel at around 3000-4000 rpm, which leaves anything above 4700 rpm weak.
Is it possible to adjust the IP so that it will not start cutting fuel but continue until about 6k rpm?
This way we can get more power without major changes.
Forced Induction knows all about that. He has a post on here detailing the guts of the IP in an OM617 application.
I know it is possible, but I doubt it would be recommended.
(01-10-2010, 05:43 PM)Deni Hi,
As far as I know in our diesels om617/602/603 the IP sturts cutting fuel at around 3000-4000 rpm, which leaves anything above 4700 rpm weak.
Is it possible to adjust the IP so that it will not start cutting fuel but continue until about 6k rpm?
This way we can get more power without major changes.
(01-10-2010, 05:43 PM)Deni Hi,
As far as I know in our diesels om617/602/603 the IP sturts cutting fuel at around 3000-4000 rpm, which leaves anything above 4700 rpm weak.
Is it possible to adjust the IP so that it will not start cutting fuel but continue until about 6k rpm?
This way we can get more power without major changes.
Increasing the redline is as easy as turning a screw. There is plenty of adjustment range to take the engine well beyond its safe limits.
M-Pump (spring 2m)
MW-pump
RPM is how the Finns make such high power from 2.5-3.0L diesels, upwards of 7000rpm in many cases. Jeemu for example runs up to 7400rpm on his OM605's dyno chart, though his peak power is at "just" 5600rpm.
HP is math (rpm x torque / 5252). Thats why little weed-eaters like the Honda S2000 and Mazda R8 can produce good HP figures while having crap for torque.
Personally, I prefer to have strong mid-range torque (1800-3500rpm) than to revv my engines.
Thanks for the replies.
I have already increased the max engine speed, via the 2m screw, to around 5600 rpm but after around 4800-5000 rpm there's no power up there.
Is there another screw to increase power above 5k rpm not just max rpm?
Obviously the engine won't stay there for long as it's just for brief periods of time, i.e. 1st 2nd and 3rd redline (more like 1st and 2nd).
Jeemu can tell more about his setup, but shortly: that high revs (over 7k) was an "accident". Most Finnish 60x turbos don't rev over 6k, there's no sense because max power is around 5000-5500 rpm.
My 606 revs about 6400rpm, but max power is also around 5500. It's with a built N/A 603 pump (1987) and the gorverning spring is the stock one. Preloaded about 2mm and screwed to the max (not enough thread to screw further with the stock bolt). Even if there were more thread, tightening more would end up in a situation in which the spring max travel becomes too short, so it can't cut fueling enough anymore (and engine could over-rev).
If one wanted the "limiter" to be quicker (the rev range between non-cut fueling and no fueling at all is short) one would have to lighten the counterweights and install a weaker, longer and thus more preloaded spring. Don't see the need for this, as these don't produce good power above 6k with stock cam(s) etc..
I also have another 603 N/A pump (1993) and that has a slightly shorter spring.
I'm not looking for 10k rpm .
My idea is if the turbo om602 makes about 126 hp at 4600 rpm thats roughly 144 torque. So if we keep the same torque thus fuel up to about 5500 rpm we would have about 150 hp.
The problem I have with power down low is torque. I'm already about to kill my 5 months old clutch. With LPG on and in 3rd - 4th - 5th it already slips at WOT.
Or if we max out the stock IP that is roughly 150hp at 4600 rpm that means almost 180hp at 5500 rpm.
But efficiency decreases quickly as rpms rise in diesels. That's why the (stock) fueling starts to cut off so early, to prevent smoking.
Haven't found a diagram for OM60x, but for OM617.
~270g/kWh @ 1500-2000rpm
~290g/kWh @ 3000rpm
~345g/kWh @ 4400rpm
For example, burning the same amount of fuel at 2000rpm and 4000rpm doesn't produce 120% more power in the latter, only 72% more. Only in theory, of course, but you'll get the point.
there is a spring capsule. The spring itself has a certain colour. The spring tension can not be changed in the capsule (not a an adjustment) but there is a checking procedure "if not o.k. change the capsule" (Bosch instructions).
Different springs are no more available, AFAIK and not foreseen to be touched (also Bosch instructions).
I am not yet at the point to put my hands on the spring (-tension) but this is the thing that builds the fuel curve (cut off).
Tom
(01-11-2010, 05:34 AM)muuris Jeemu can tell more about his setup, but shortly: that high revs (over 7k) was an "accident". Most Finnish 60x turbos don't rev over 6k, there's no sense because max power is around 5000-5500 rpm.Yes that high rev was accident. Mynä has replace the spring and i tight it too much. Now it revs 6200rpm.
(01-11-2010, 05:34 AM)muuris Jeemu can tell more about his setup, but shortly: that high revs (over 7k) was an "accident". Most Finnish 60x turbos don't rev over 6k, there's no sense because max power is around 5000-5500 rpm.Yes that high rev was accident. Mynä has replace the spring and i tight it too much. Now it revs 6200rpm.
(01-11-2010, 04:01 PM)jeemu Yes that high rev was accident. Mynä has replace the spring and i tight it too much. Now it revs 6200rpm.
Engine has stiffer valve springs and better retainers, but original cams.
I ordered new mechanical cam followers and friend make new cams.
Hope ther max power come 6000rpm and numbers starts at 5
So i can concentrate that new projeckt engine.
(01-11-2010, 04:01 PM)jeemu Yes that high rev was accident. Mynä has replace the spring and i tight it too much. Now it revs 6200rpm.
Engine has stiffer valve springs and better retainers, but original cams.
I ordered new mechanical cam followers and friend make new cams.
Hope ther max power come 6000rpm and numbers starts at 5
So i can concentrate that new projeckt engine.
(01-23-2010, 09:58 PM)Gurkha Won't high rpm increase the chance of throwing the crank on diesels?
(01-23-2010, 09:58 PM)Gurkha Won't high rpm increase the chance of throwing the crank on diesels?
(01-24-2010, 11:42 AM)Deni If the increase in power is linear with the increase in rpm then we are looking at about 16% increase in power.
(01-24-2010, 11:42 AM)Deni If the increase in power is linear with the increase in rpm then we are looking at about 16% increase in power.
(01-24-2010, 12:34 PM)ForcedInduction However, the 617's torque steadily drops after 3000rpm causing horsepower to fall after 3800rpm.
For a stock engine (just for my point, I know modifications will change the numbers), if the torque continues to drop at the same linear rate you'll have about 65lb/ft of torque at 5500rpm and produce only 68hp.
(01-24-2010, 12:34 PM)ForcedInduction However, the 617's torque steadily drops after 3000rpm causing horsepower to fall after 3800rpm.
For a stock engine (just for my point, I know modifications will change the numbers), if the torque continues to drop at the same linear rate you'll have about 65lb/ft of torque at 5500rpm and produce only 68hp.
(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
My original question was, is there any scew i can turn to delay the fuel cut off?
(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
My original question was, is there any scew i can turn to delay the fuel cut off?
(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
(01-24-2010, 01:06 PM)Deni My original question was, is there any scew i can turn to delay the fuel cut off?
(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
(01-24-2010, 01:06 PM)Deni My original question was, is there any scew i can turn to delay the fuel cut off?
(01-25-2010, 11:06 AM)muuris(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
You're wrong! Now that I got your attention, read backwards and look at my earlier post, #8.
(01-25-2010, 11:06 AM)muuris(01-24-2010, 01:06 PM)Deni My original question was, is there any scew i can turn to delay the fuel cut off?
Yes there is. Look at this topic and the M-pump section in it.
(01-25-2010, 11:06 AM)muuris If it were that simple, why would MB limit their diesels to rev only 5k, why not 10k and have twice the power...
(01-25-2010, 11:06 AM)muuris(01-24-2010, 01:06 PM)Deni As far as I know, correct me if I'm wrong, the decrease in torque comes because fuel starts being cut off at 3k rpm, until about 5150 rpm on a stock pump when all fuel is cut off.
You're wrong! Now that I got your attention, read backwards and look at my earlier post, #8.
(01-25-2010, 11:06 AM)muuris(01-24-2010, 01:06 PM)Deni My original question was, is there any scew i can turn to delay the fuel cut off?
Yes there is. Look at this topic and the M-pump section in it.
(01-25-2010, 11:06 AM)muuris If it were that simple, why would MB limit their diesels to rev only 5k, why not 10k and have twice the power...
Smoke is all the 617 makes on the top end. I'm pumping 18 intercooled psi and it still smokes with high EGTs at full throttle. The 5.5mm plungers just take too long to completely inject when turned all the way up and the 2-valve uniflow head can't move enough air without more pressure (which Garrett's turbos can't supply without overspeeding). Hopefully my Holset will fix that last issue.
Messing with the torque control makes the engine very slow to return to idle (it won't go down at all if you turn it up too high) and prevents deceleration fuel cutoff.
(01-25-2010, 10:27 PM)ForcedInduction Smoke is all the 617 makes on the top end.
(01-25-2010, 05:05 PM)Deni Read the post. Even if efficiency goes down, there's still some gain at top end.
(01-25-2010, 05:05 PM)Deni Now I see, it is the torque control. Thanks
(01-25-2010, 05:05 PM)Deni Read the post. Even if efficiency goes down, there's still some gain at top end.
(01-25-2010, 05:05 PM)Deni Now I see, it is the torque control. Thanks
(01-26-2010, 09:39 AM)muuris No, not that. Max rpm is rised by tightening #23. If you do something with #17, loosen it a bit.
(01-26-2010, 09:39 AM)muuris No, not that. Max rpm is rised by tightening #23. If you do something with #17, loosen it a bit.
(01-26-2010, 11:23 AM)Deni Steam that I guess torque control will solve.
(01-26-2010, 11:23 AM)Deni Steam that I guess torque control will solve.
(01-26-2010, 11:23 AM)Deni I've already risen max rpm to about 5.8k rpm in neutral and 5.5k in 1st or 2nd, but it looses steam after about 4.8 - 5k rpms. Steam that I guess torque control will solve.
(01-27-2010, 09:54 AM)muuris(01-26-2010, 11:23 AM)Deni I've already risen max rpm to about 5.8k rpm in neutral and 5.5k in 1st or 2nd, but it looses steam after about 4.8 - 5k rpms. Steam that I guess torque control will solve.
What if your governor spring is just old and has lost its best tension?
(01-27-2010, 09:54 AM)muuris(01-26-2010, 11:23 AM)Deni I've already risen max rpm to about 5.8k rpm in neutral and 5.5k in 1st or 2nd, but it looses steam after about 4.8 - 5k rpms. Steam that I guess torque control will solve.
What if your governor spring is just old and has lost its best tension?
(01-28-2010, 01:15 AM)muuris That wasn't a question, but a guess why yours won't rev up higher (like others). If the spring tension is weakened, it will act (lessen fueling) on lower rpms.
muuris What if your governor spring is just old and has lost its best tension?
(01-28-2010, 01:15 AM)muuris That wasn't a question, but a guess why yours won't rev up higher (like others). If the spring tension is weakened, it will act (lessen fueling) on lower rpms.
muuris What if your governor spring is just old and has lost its best tension?
(01-29-2010, 02:17 AM)muuris(01-28-2010, 02:38 AM)Deni There might be many culprits, but IMO the reason it is not strong above 5k rpm has more to do with fuel cut off than anything else.
Has anyone disagreed with that? Find another spring and try with it.
(01-29-2010, 02:17 AM)muuris(01-28-2010, 02:38 AM)Deni There might be many culprits, but IMO the reason it is not strong above 5k rpm has more to do with fuel cut off than anything else.
Has anyone disagreed with that? Find another spring and try with it.
the fuel curve over rpm is not linear because airflow is not linear in the (high range) rpm.
AFAIK it is the small spring in the spring capsule that determines the bending of the fuel curve. Post#9
Allowing the governor to provide just higher rpm is different (easier) adjustment.
Tom
(01-30-2010, 03:04 AM)tomnik the fuel curve over rpm is not linear because airflow is not linear in the (high range) rpm.
AFAIK it is the small spring in the spring capsule that determines the bending of the fuel curve. Post#9
Allowing the governor to provide just higher rpm is different (easier) adjustment.
Tom
(01-30-2010, 03:04 AM)tomnik the fuel curve over rpm is not linear because airflow is not linear in the (high range) rpm.
AFAIK it is the small spring in the spring capsule that determines the bending of the fuel curve. Post#9
Allowing the governor to provide just higher rpm is different (easier) adjustment.
Tom