Engine/Transmission (1998.5 - 2002) 2100 rpms for a period of time?

[JMalliet]

I'm towing 12k pounds this weekend for 2 hours one way. I took it out for a drive to see how it towed before I made the trip. With the Edge on 2x2 my EGT's were at 850* in 5th gear at 2100 rpm's (60mph). I tried 6th and EGTs were at 1000-1100* at 1600 rpm's. The truck has 3. 55's and 315's, thats why the rpm's are lower then normal. Also the engine temp got up past 190* alittle, probably between 195-200*, held there for a few minutes. Is it ok to run at 2100 rpm's for a long time? It's not going to hurt the engine at all is it? What about the engine temp, does that seem ok?

 

[Oil Burner]

2100 is fine. Only downside I have found driving at 2300 or more is that my fuel mileage goes down fast! Without those 315s you would probably be turning that RPM in 6th gear anyway. Imagine if you were stock and had 4. 10's. You won't have any trouble keeping it in 5th.



Have fun.

 

[JMalliet]

With the 295's im actually turning 1800 rpm's at 60mph, which I still think would cause my EGT's to be to hot. I was told stock trucks with 4. 10's turned 2100 rpm's at 60mph. I wouldn't think it will hurt it then, does the engine temp sounds like its acting right? How hot can these engines safely get? I don't want to be wondering that on my trip if the temp happens to get past 200*.

 

[Oil Burner]

Well, I guess all I can say is that I have never seen mine go past 200*. But I always tow with the comp off and run on just injectors and I have only towed more than 10,000 lbs once with 35" tires and these supermental injectors.



Make sure your rad is clean (especially if you have the factory crank case vent setup!).



Jason

 

[GCULP]

these things will run 2100 rpm all day long, don't worry, just gonna cost a little more in fuel, but better than cookin it.

 

[Big A]

Can you bump your speed up a bit, to about 65. That should put you at close to 1800rpm.

Big A

 

[Thomas]

... Is it ok to run at 2100 rpm's for a long time?...

I assume you are questioning if sustained 2100 RPM is too high. From the August, 1999 Cummins Power Booster News:

... The new 24-valve engine likes to be driven hard. It performs best in the higher RPM ratings... For optimum performance while pulling a heavy load, run up to 2800-3200 RPM. You can hit the hill at 3000-3200 RPM and allow your engine speed to drop to 2300 RPM before downshifting...

And, from Dr. Diesel's Q&A section of the same newsletter:

Q: My 24-valve Cummins/Dodge is a work truck and I run at 3000 RPM all day long pulling a medium load (9,500 lbs. ). How is this affecting my engine?

A: The Dodge 24-valve will run all day long at 3000 RPM. This does not cause any problems other than increased fuel consumption...

I think you're good-to-go at 2100 RPM.

 

[Nate]

I normally set my cruise at 2000rpm, which is about 72 mph.

 

[GOTSOOT]

200* is perfect!hot engines will wear better than a colder one, say @ 160* all the time, or cycling.

 

[Nate]

I've seen my engine hit 190* a few times, but normally it runs in the middle of the first line and 190*

 

[RustyJC]

See signature. 70 MPH with 4. 10 gears = 2350 RPM. I've run on the Interstates for days at 70-75 MPH towing our 5th wheel, and the only damage is to fuel consumption. EGTs at these speeds are around 700 - 750 degF.



Rusty

 

[JMalliet]

Thanks everyone for the responses. I want this engine to last along time, now I feel better about running it in 5th while towing heavy.



Big A, I can not go any faster then 60mph. I will be in 55mph zones the whole way.

 

[Big A]

Thanks everyone for the responses. I want this engine to last along time, now I feel better about running it in 5th while towing heavy.



Big A, I can not go any faster then 60mph. I will be in 55mph zones the whole way.

I understand fully. I've been in the same boat as you, and I chose direct gear instead of overdrive.

Big A

 

[JasonCzerak]

See signature. 70 MPH with 4. 10 gears = 2350 RPM. I've run on the Interstates for days at 70-75 MPH towing our 5th wheel, and the only damage is to fuel consumption. EGTs at these speeds are around 700 - 750 degF.



Rusty

From Minneapolis,MN to Mt rushmore, SD in a weekend. Most of the 1400 miles was near 2500rpm and 85mph (295 tires). Boost at about 16-18psi. 22-24 on some hills. . UNLOADED.



I got about 14-15mpg. The multiple 85-108mph runs here and there didn't help that much. But the motor sure ran quiter after that trip for about a week.

 

[Jeepmullet]

my best fuel economy isnt at low RPMs in 6th gear, but at high RPMs in 5th gear.

 

[Big A]

my best fuel economy isnt at low RPMs in 6th gear, but at high RPMs in 5th gear.

I'm not doubting you, as I have heard this repeatedly. However, if you look at where these engines make the best torque/hp , it's at the 1800 to 2200 rpm range.

Big A

 

[RustyJC]

I'm not doubting you, as I have heard this repeatedly. However, if you look at where these engines make the best torque/hp , it's at the 1800 to 2200 rpm range.

Big A

Ummm... . peak horsepower on my dyno run (and on the rating sheet) is 2700 RPM. Peak torque with my mods on the dyno was at 2200 RPM, but that may be where the turbo finally spooled up (darned inertial dynos!) :-laf



To find where the engine is most efficient, one would really need a BSFC curve.



Rusty

 

[Big A]

I couldn't agree more Rusty. But you said yourself. Your peak torque was at 2200 RPM. I bet your torque begins to fall after that, as your hp increases. Thats the beauty of the Cummins vs the 6. 0 powerstroke, and the duramax. You can do alot more work at lower rpms, therefore making it more efficient.

Big A