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+--- Thread: HIgher RPM for more power? (/showthread.php?tid=1016)
HIgher RPM for more power? - Deni - 01-10-2010
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.
RE: HIgher RPM for more power? - Nick - 01-10-2010
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.
This is the thread, if you're tuning a Federal OM617, you'd have the MW pump, the exclusive M-pump was only on the Euro 617's.
I am not aware if there is a thread of the 60x engine IP adjustments, give it a search.
Thread:
http://www.superturbodiesel.com/std/ip-full-load-adjustment-procedure-for-mw-pumps-t-189.html
RE: HIgher RPM for more power? - OM616 - 01-10-2010
(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.
Significant Torque Control and the Main Spring adjustments, or change the Flyweight springs out with stronger ones. Both will require Idle and Throttle Springs to be adjusted in response to the Torque Control or Flyweight spring change.
To get that high you may have to change the Main Spring screw because the stock one may not be long enough to get you there without changing the Main Spring out with a stronger one.
I’ve done it on 616 and 617. You will have to remove the plate off the back of the Governor to get to the adjustments. Not easy on 617, not sure on others. It is very easy to loose control of an adjustment during the adjustment with it on the car, you have to work with your finger tips.
Generally not recommended as a do it your self. Can result in a run away / over-rev blow up on initial start up if not set up properly.
RE: HIgher RPM for more power? - ForcedInduction - 01-11-2010
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.
RE: HIgher RPM for more power? - Deni - 01-11-2010
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).
RE: HIgher RPM for more power? - muuris - 01-11-2010
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.
RE: HIgher RPM for more power? - Deni - 01-11-2010
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.
RE: HIgher RPM for more power? - muuris - 01-11-2010
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.
RE: HIgher RPM for more power? - tomnik - 01-11-2010
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
RE: HIgher RPM for more power? - jeemu - 01-11-2010
(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.
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.
RE: HIgher RPM for more power? - GREASY_BEAST - 01-11-2010
(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.
Have you experienced valve float in the stock 602? At what RPM did it occur? What about a 617?
RE: HIgher RPM for more power? - Gurkha - 01-23-2010
Won't high rpm increase the chance of throwing the crank on diesels?
RE: HIgher RPM for more power? - Deni - 01-24-2010
(01-23-2010, 09:58 PM)Gurkha Won't high rpm increase the chance of throwing the crank on diesels?
I think you guys are missing the point.
What I'm suggesting is not to create a rev happy diesel.
What I'm saying is having the peak power raised from 4.6rpm to about 5.5k rpm. If the increase in power is linear with the increase in rpm then we are looking at about 16% increase in power.
RE: HIgher RPM for more power? - ForcedInduction - 01-24-2010
(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.
Not quite. You'll get some power because the math allows RPM to easily produce high figures, as long as torque stays constistant. Thats why an F1 engine can have 900hp with less torque than the average V6 sedan. 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. Less than an OM616. Acceleration will be slower than if you had shifted to keep the engine at it's torque peak.
Attached is a chart of all my dyno runs to date to illustrate.
RE: HIgher RPM for more power? - Deni - 01-24-2010
(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.
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?
RE: HIgher RPM for more power? - tomnik - 01-24-2010
post #9!
Tom
RE: HIgher RPM for more power? - Kiwibacon - 01-24-2010
(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?
It cuts the fuel to prevent smoke because the engine doesn't breathe well (VE drops) as rpms rise.
To beat this you would need a turbo sized just for high rpm flow, but drivability would suck and in daily driving your car would be slower.
RE: HIgher RPM for more power? - muuris - 01-25-2010
(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.
(01-24-2010, 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.
If it were that simple, why would MB limit their diesels to rev only 5k, why not 10k and have twice the power...
RE: HIgher RPM for more power? - Deni - 01-25-2010
(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.
Read the post. Even if efficiency goes down, there's still some gain at top end.
(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.
Now I see, it is the torque control. Thanks
(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...
If MB didn't max out the IP in the first place than we shouldn't either
.Well as I said, I'm not looking for a rev happy honda, just stronger topend.
RE: HIgher RPM for more power? - ForcedInduction - 01-25-2010
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.
RE: HIgher RPM for more power? - Deni - 01-26-2010
(01-25-2010, 10:27 PM)ForcedInduction Smoke is all the 617 makes on the top end.
What about the om602? I guess not much better but still.
RE: HIgher RPM for more power? - muuris - 01-26-2010
(01-25-2010, 05:05 PM)Deni Read the post. Even if efficiency goes down, there's still some gain at top end.
The point was that the gains aren't so big without compensating the weaker efficiency by boost.
(01-25-2010, 05:05 PM)Deni Now I see, it is the torque control. Thanks
No, not that. Max rpm is rised by tightening #23. If you do something with #17, loosen it a bit.
RE: HIgher RPM for more power? - Deni - 01-26-2010
(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.
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.
RE: HIgher RPM for more power? - GREASY_BEAST - 01-26-2010
(01-26-2010, 11:23 AM)Deni Steam that I guess torque control will solve.
You can only go so far with this though, return-to-idle issues take over before significant gains are made. Let us know if this problem in the TC adjustment is augmented by your increased high idle.
RE: HIgher RPM for more power? - muuris - 01-27-2010
(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?
RE: HIgher RPM for more power? - Deni - 01-27-2010
(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?
You can't reply to my question with a question
.I don't know what happens.
RE: HIgher RPM for more power? - muuris - 01-28-2010
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.
RE: HIgher RPM for more power? - Deni - 01-28-2010
(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?
You ended yours with a question mark so that makes it a question in my eyes
.Joking.
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.
When I had the IP removed to play with the full load and "high idle" I read the torque control shouldn't be touched that's why I left it alone.
I'll have to try to remove the back plate of the IP without removing the IP as it is a PITA.
Another thing I saw is that with LPG turned on it is more eager to rev than with it off, so obviously there's lack of fuel.
RE: HIgher RPM for more power? - muuris - 01-29-2010
(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.
RE: HIgher RPM for more power? - GREASY_BEAST - 01-29-2010
(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?
Am I missing something or can't you just turn a screw to make the high idle go up? Why do you need another spring? Is the M Pump different than MW in this regard?
RE: HIgher RPM for more power? - tomnik - 01-30-2010
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
RE: HIgher RPM for more power? - GREASY_BEAST - 01-30-2010
(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
Ah, I see. Thanks for the clarification.