RPM whats normal max RPM

[cummins2go]

Hi what is the maximum RPM that these motors should turn when you free rev not under a load mine revs to 3000 RPM but when on road doesn't seem to rev over 2700 RPM look at signature I don't know if pump has been touched or not except for timing any thoughts I want a little more power not sure what I should try next everything so far has given it a lot of power but not enough yet

Darrin

 

[BushWakr - RIP]

Personally I really dislike the idea of "free reving".

Pretty well all of these engines will do that, and it doesn't really tell you much.

The 2700 figure is much more telling. Normally an untouched pump will ususally top out at around 2450-2500, under throttle in gear. That is, it will no longer pull hard, and has defueled. It kinda feels like the truck "fell on its face" so to speak.

If you are seeing the engine run up to 2700 while working then the pump has been tweaked a bit.

Next time your out, put trans in 2nd, start out and get on the throttle hard... watch the tach as you accelerate and when you feel the truck start to "fall off" that is you defuel point. Now, you will see a bit more RPM after that point, but defuel is were the power drops dramatically.

I use 2nd gear because its not so darn fast that I can't take my eyes off the road for few seconds.

You can increase the governed speed of these up as far as 3000 RPM. Some have gone into the 3300 RPM range, but personally that is into the "too much wear and tear" for my daily driver.

Also you'd likely need the heavier valve springs because its reaching/at the "float" point by then.

With the auto trans. setting the governor at around 2800-2900 is great. You get the RPM that the stock TC/transmission needs to really hook up properly.

Be sure to watch EGT's and transmission temps too.



I hope thats not too convoluted an explanation

 

[sgriffing]

Newbie question

How do you turn up the Gov on these?

 

[cummins2go]

Thanks Bushwakr I will try that next time I take it out. What should I do for more power. going to put the old smoky BHAF mount on soon any other cheap power up grades that I should do I was under the impression these motors can run wide opened all day. I have seen cummins with pumps run wide opened for hours are these different from the one's in our trucks

Darrin

 

[BushWakr - RIP]

These engines are used in various configurations for all sorts of applications... marine, industrial, gensets and others.

They are set up differently for each, with some similarities, but are basically the same motor.

You can run them "wide open" for long periods so long as you keep the limitations in mind.

If you expect to run them at 3600 RPM all day then best of luck in my opinion...

But... I don't think you would have any problem (assuming the engine is well maintained and in decent shape) running 3000 RPM for extended periods. Your limitations are the obvious ones like EGT's, oil levels/changes, filters, etc.

I have heard, heard mind you, that when you get into the 3300 and up range, you should be looking at valve spring changes or you'll "float".

As for the governor adjustment I'll attach a link that has pics I've posted on a couple related items.

If you look at the AFC housing, just below it and slightly to the rear you'll see a tamper cap. (assuming it's still there) Under that cap is the "high idle adjustment"

Its a long screw just like the idle screw, except this one has 2 locknuts on it (10mm I think)

Mark the screw first, then loosen the nuts. Backing the screw OUT of the bracket will increase the high end RPM.

You'll need to have someone in the truck work the gas peddle. Watch the throttle open and be sure that the throttle stop plate makes contact with the screw end... just like the other end of the plate should touch the idle screw at rest.

Assuming it's untouched, you should be able to back out about 1 1/2 turns as a start. Test drive then go from there.

You must make sure the breakover spring is properly adjusted afterward as well... . here's the link to the post with pics...



http://216.235.147.117/forums/showthread.php?threadid=21040





Bob.

 

[JLEONARD]

Just a quick comment on "free revving" rpm.

This is a must check in the marine application. Called 'no load' or 'high idle' it is first necessary to know that the pump is set correctly in order to insure that the prop size and hence engine loading, yields the correct rpm at WOT (wide open throttle).

According to marine techs, it does not harm the engine and is repeatable at almost any stage of the engine's life unless there is a major problem, because the engine develops no horsepower without a load.

At least that's how it was explained to me from several sources.

My new Cummins marine engine had a total of 15 minutes of idle time on it, just enough to insure everything was up to temperature before the Cummins tech did a no load check on it. Standard proceedure.

It is scary, to watch a human straddle the engine (private parts too close for my comfort) , optical tachometer in hand, and shove the pump lever right to the firewall (or bulkhead in boatspeak).

Just another view.

 

[DieselBuzz]

Is there a spin doctor in the house?

First excuse my pun. Now on my original engine and pump I felt the defueling happen right at the 2500rpm mark. Now that I have had the pump rebuilt to standard "Bosch" specs. I defuel around 2700 to 2800rpm. Did the tech use the wrong specs? make a mistake? I don't know. I do know that the pump performs the same in every other way. Low idles around 750 to 800, power feels the same, smokes the same at the top end. The higher limit in my opinion makes the truck easier to drive,(4. 10s). I do not push the limit that often or keep it there for long. I try to balance the costs and the benefits. My 2 cents.

 

[BushWakr - RIP]

JLEONARD said... ... " It is scary, to watch a human straddle the engine (private parts too close for my comfort)... "



Well all I can say is ... . if that were me, all private parts would have departed for a holiday loooongggg before they would submit to being hung over one of these babies under those conditions. .



Seriously though, I think you are dead right, it's just that I can't get my head around the idea of wacking it wide open and just watching it to see what happens... . musta been the time we did that with a gasser and put a rock on the pedal to see what would happen... ... ugly !!!!

Mind you in the maual it does say "... . to test high idle... "

so there ya go.

See, just talking about this and they up and took off..... now, were did those little boogers get to... ... ... ... ...



Bob.