high rpm operation.

[cmills]

Reading the owners manual it says to not run the engine at high rpms for extended perionds of time, what is considered high rpms? My 99 has been ran at probably 2,800rpm or so quite a few times for extended periods of time down the interstate with no issues, what makes these any different? Or is talking about running it at redline for long stretches? I would think these could run all day long at 3,000rpm if needed without any problems or am i missing something.

 

[AH64ID]

Are you referring to the caution on page 152? It gives the rpm in the caution.

Do not operate the engine with the tachometer
pointer at high RPM for extended periods. Engine
operation over 3200 RPM (Redline) can result in
significant damage that will not be covered under
warranty.

 

[JLandry]

Or is talking about running it at redline for long stretches? I would think these could run all day long at 3,000rpm if needed without any problems or am i missing something.

Here's the text from the owner's manual:

CAUTION!

Do not operate the engine with the tachometer pointer at high RPM for extended periods. Engine operation over 3200 RPM (Redline) can result in significant damage that will not be covered under the New Vehicle Limited Warranty.​

I interpret this to mean avoid running the engine continuously in something like the 2800-3200 rpm range. Obviously anything above 3200 rpm is an absolute no no.

However, the specifics of this would be a great question to ask Cummins or Dodge. Maybe we'll have the chance to do so at May Madness if they're present.

John L.

 

[AH64ID]

If either one of you want to PM me you ESN I can see if quickserve has any info on rpms.

With the rated rpm being 2800 you should be able to run that all day long.

I read that warning as don't exceed 3200 for extended periods. Do the new tachs even have a redline?

 

[JLandry]

Do the new tachs even have a redline?

My 2014 3500 does.

John L.

 

[Wingate]

TEL( top engine limit) should be set in the engine ECU. Engine shouldnt go beyond that unless there is a quick to neutral from a full power condition such as shoving in the clutch at full power. Of a forced overrun of the engine by trying to decend a hill in too low of gear with too much weight behind it.

 

[slingshot383]

I try to keep mine below 2000 rpm, what would you be doing to have the engine screaming at 2800 or more for any duration?

 

[AH64ID]

TEL( top engine limit) should be set in the engine ECU. Engine shouldnt go beyond that unless there is a quick to neutral from a full power condition such as shoving in the clutch at full power. Of a forced overrun of the engine by trying to decend a hill in too low of gear with too much weight behind it.

Yup, the current ISB has a 4200 rpm for 15sec limit on overspeeds.

I try to keep mine below 2000 rpm, what would you be doing to have the engine screaming at 2800 or more for any duration?

Pulling a big hill with a big load. HP is still just as important as torque, or even more important once up to speed.

 

[cmills]

I know when plowing snow with my 99 I will rev it up pretty high when backing up across parking lots, just do to the fact it is so slow and there have been times when in 4 low that it will be revved up pretty good when pulling something in the mud or real soft soil when I don't want to lose speed by shifting gears. But I'm only talking about 30-45 seconds at a time not for an extended period. I could be wrong but I think the 2012's were rated at 3000 rpm or a little over, and like AH64ID said I would think they could run all day at the rated RPM without harming anything. Yeah it might cause a little more wear and definitely burn more fuel but running 2000 rpm probably causes more wear than 1500 rpm.

 

[BIGNASTY]

I try to keep mine below 2000 rpm, what would you be doing to have the engine screaming at 2800 or more for any duration?

I would like to know this also?

 

[JR]

Max horsepower. You may reach peak torque at 1600 rpm but with a heavy load in tow the minute you begin ascending a hill power will fall off much quicker than compared to running 2800 rpm.

 

[slingshot383]

I guess mountain driving might make things different, I haven't had any of those issues in the Ozarks.

 

[NIsaacs]

I would think these could run all day long at 3,000rpm if needed without any problems

I think "if needed" is the key word here. With your '99, 5spd (one overdrive) and 4.10's you probably needed high rpm if you wanted to get somewhere in one day. However with your new truck, 6spd (two overdrives) and 3.73's you will never need it, so it is kind of a non issue. Cummins rates the 6.7 for 2600 rpm, Dodge rates it to 3200 to make it more user friendly, especially back in the 4 and 5 spd days.

Nick

 

[AH64ID]

However with your new truck, 6spd (two overdrives) and 3.73's you will never need it, so it is kind of a non issue. Cummins rates the 6.7 for 2600 rpm, Dodge rates it to 3200 to make it more user friendly, especially back in the 4 and 5 spd days.

Nick

Gearing is huge but at some point rpms will win out, if needed. I am not sure the double OD's really reduce the need as much as the power increase, since if you are using OD you aren't demanding as much hp/tq as if you downshift for a big grade. With the amount of power these trucks make it does take a big load to require the rpms. A '13 Aisin has more flywheel hp at 1600 rpms than any 2nd gen truck did peak, at 259 hp @ 1600 rpms. Assuming a fairly flat torque curve the Aisin makes 325hp around 2000-2200 rpms, vs 2900 on the highest hp 5.9 ever put in a pickup. It's has really lowered the rpms required, but if people are using them at GCWR there will still be a need for lots of rpms.

Personally I never seem to need more than 2500 rpms when towing. It gets me all the speed and power in any gear, but I have ridden in older auto Dodge's that run 2500-2800 often.

I am not 100% sure on the 6.7, but on the HPCR 5.9 it's allowed 3200 rpms but anything above rated rpm starts to derate and defuel so by the time you hit 3200 you are down on power. The 07.5-12 6.7 had a 3013 rpm rated power, and the 13-14 had a 2800 rpm rated power. That's the peak that should be used when towing, as above that your start losing hp/tq very quickly.

The rated rpm is based on application, some 5.9's in the QSB platform are rated at 3400 rpms and some at 2200. The QSB 6.7 has ratings up to 3300, while the highest I have seen is 2800 in a non-Dodge application.

 

[Wingate]

this new one was cruising at 83 mph @ less than 2K RPMS!...

 

[orhusky]

The highest RPM I ever see are not going up hill with a load, I can pull any hill I have seen out west @ 2400RPM or less in 4th, but on the down hill side of the grade. I will set the cruse at 5 mph less than what I want my max down hill speed to be and let the ECM/EB take over from there. It down shifts to get the RPM's in a range that will hold the speed in check and I see 2600-2900 RPM before the max breaking kicks in.

 

[RVTRKN]

Even though I only have 52K on the ODM, at 25K miles, I ran mine up the south bound Grape Vine at a GCVW of 23K and 2800 RPM from a 1/4 of the way up, to the top, and it sounds as if its new. High RPM's keep the HP up, as well as maintaing the torque needed. Look at the torque curve, you still have very high torque at that RPM, but the HP is also peaking. I needed to stay out of the slow truck lane where the trucks are lucky to run at 20MPH or less, and a fully loaded truck at 80K GCVW can crawl at a snails pace.

 

[Cummins12V98]

this new one was cruising at 83 mph @ less than 2K RPMS!...

That's nuthin! Mine turns 2,300rpm at 104mph.