Engine/Transmission (1994 - 1998) Driving At High RPM's

[MKline]

I live in a town with long streches of road with speed limits of 45 and 50 MPH. This seems like it is just in between gears for my auto. It luggs in overdrive, and it runs at about 2100 RPM,s with the OD off. My guess is that it is better to run at higher RPM's than to lugg it. Just looking for an opinion.

 

[Forrest Nearing]

yes... although at that speed w/ no load, it's more like "loafing" than lugging... because with your auto, it's going to downshift and or come out of lockup when it needs too.



the main reason to leave it in D is to save wear on your transmission from shifting in and out of OD

 

[DRAG DIESEL]

and it runs at about 2100 RPM,s with the OD off. My guess is that it is better to run at higher RPM's than to lugg it.

Those are not high rpm's. Your fine at 2100.

 

[MKline]

I guess another question would be, should you drive at 2100-2300 RPM for an extended period of time? Like say 30 minutes.

 

[Champane Flight]

Yeap

It is just fine, as long as you are not on governor.

 

[DRAG DIESEL]

I guess another question would be, should you drive at 2100-2300 RPM for an extended period of time? Like say 30 minutes.

With the Stock Govenor, the engine is designed to run at wide open throttle it's entire life.

 

[biggy238]

Perfectly safe... . I run mine about half and half 3rd/4th. IT's other crap that will get you. But like they said... IT Governors well within it's maximum operating range... . You can't hurt it when it's stock...

 

[chazj]

Does my '02 also have a governor that prevents my stock truck from over-reving??

If this is the case... then potentially I could put the "pedal to the metal" and it would max out at 3200 rpm and be able to sustain that indefinately???

 

[Joe G.]

From what I've read the 12 valve engine is designed to run at 2300 RPM with a load on it as long as you can stand it. It's common for a marine engine to run at high RPM for days at a time going somewhere in a boat.

 

[NHays]

Not trying to steal the thread. I will be keeping my eye on this one. I am also interested on a max sustainable RPM. I would like to know this because i do alot of towing and have 3:54 gearing at 70 mph i am at about 2000 RPM. Things get a little toasty at that rpm up a hill. I was under the impression that if you ran under redline all the time that you are withing the operational range of the engine. I know a case tractor with an 8. 3L runs at 23-24 hundred all day and no harm done there, and thats loaded. I also read somewhere that our little engine comes apart well in the 5K rpm range. Yes, to do that test they had to heavily modify the stock engine. But anyways. I wonder what cummins says about the usable rpm range of the engine. thats my . 02 cents for now.



Sorry for the long post

 

[chazj]

I found some information that I had printed up from a Cummins website. The engine involved is a 2001 24 Value CTD... which I figure is close enough to my 2002 HO CTD.

At anyrate it was stated that the peak torque range was from 1600 to 2700 rpm and power extended to 3200 rpm.



IF I am reading this correctly... I guess you could run all day long between 1600-2700 rpm and up to 3200 rpm at which point the governor takes over and holds your rpm's to that point. IF it's like the farm tractors I have run... I would think you could run it at 3200 rpm all day without risk to the engine...

 

[Champane Flight]

No problem

You can run against the governor all day and night, I would not say it is good for the pump, governor springs, or internals of the pump. The engine has no problem at this RPM, in fact I believe 4800 is about the top on a B-series. That is before you start hurting stuff on a stock engine. If you want to modify, stronger vlave springs, balanced crank and internals maybe more. .



Things start getting toasty up that hill at 2000 with a load because of lugging? Can your engine accelerate under that load?

 

[NHays]

[/QUOTE] Things start getting toasty up that hill at 2000 with a load because of lugging? Can your engine accelerate under that load? [/QUOTE]





Yes, I can still accelerate. but I can tell the engine has left its optimal working range. My main Q was I can run in fourth gear all day long at 65 mph pulling, just my truck does not run too well at that RPM. Also I am having some work done to it at this time and expect a big change in drivability (I had a stuck piston, bad injectors and bad DV's). Look under resent threads of NHays.

 

[MKline]

If I put in 3K GSK kit, could you still run at 3000 RPM all day long? Or is that pushing it?

 

[NHays]

If you put the 3K GSK you will be able to run the engine at a higher RPM. The reason for getting a 3K GSK is to "Trick" the governor from its stock setting of defueling the engine around 2200 rpm and give it full fuel until around 3000 rpm. However in doing so, you have the ability to run the engine past its governed rpm. Anything past the stock setting could "technically" damage the engine. I personally have the 3K kit and 60lb valve springs that I added. I don't make it a habit to run any longer than a few seconds past redline. I got the 3K kit to allow the engine to pull HARD (and I noticed a BIG difference) all the way to redline, not past it. I use my foot and feeling to govern the truck. On one occasion after I got the kit in I put my foot in it, unloaded in neutral, I scared myself when it revved all the way to 4000 RPM..... rapidly. :--) I have not done this again and will not in the future. I think 3000 RPM or a tad over is fast enough to spin our stock made engines. Just my . 02. correct me if I am wrong, sorry for the long post.

 

[NHays]

In answer to you question, YES, I belive you can run 3K all day long, but I know cruise does not go that high and you foot would have to do the regulation. :-laf

 

[MKline]

Thanks for the info. I look forward to installing the 3K GSK. It does make me wonder why some would install a 4K GSK? I have been reading old threads and it seems that some people feel the engine will come apart at 4000 RPM. Much more to learn I guess.

 

[NHays]

Yeah hey. glad we could help, or at least talk you to death... good luck.

 

[Vaughn MacKenzie]

IF I am reading this correctly... I guess you could run all day long between 1600-2700 rpm and up to 3200 rpm at which point the governor takes over and holds your RPM to that point. IF it's like the farm tractors I have run... I would think you could run it at 3200 rpm all day without risk to the engine...

One thing to remember. . . almost all Cummins B-series applications are governed to 2700 RPM, so I doubt the "run against the governor all day long" claim applies to the Ram's much-higher redline. I think you'd shorten the life of your rod bearings considerably.



Realistically though we're not gonna drive our Rams around all day long at 3200 RPM, so anyone who needs to rap it up to 2700 and hold it there for a long time towing or whatever isn't going to harm the motor. I can't think of any situation (except for maybe competition) where anyone would need to sustain over 3000 RPM for long periods of time



Vaughn

 

[biggy238]

HE has a good question... I've been floating around on here since 2004 and most accounts i've seen have said somewhere in the neighborhood of 4100rpm cummins thinks the engines fail. Now some of you on this thread are saying higher.



Are the higher rpm failures based on engines with machine work to balance the internals?





I hadn't thought about a 3k with 60lb springs but it sounds like a good idea to me. have the valve springs there so you can rev out a 3k without worrying.