New to the diesel world I am curious what I should be running for rpms,just reading the post about EGT's made me wonder maybe I am lugging my truck too much,I have a stock 03 5.9 with auto trans and 3.73 gears.I recently hauled a small 5th wheel in the mountains and was complaining about the trans shuddering or chattering at low rpm when I went to excelerate on a grade,but maybe I was just lugging it too much (rpms 1,400-1,500 with coverter locked) I would have to back off and ease into the throttle.Just felt like I was reving it too much with the O/D off?? (2,000-2,200rpm) I felt that all the torque is around 1,700 so should try to maintain this..evening when climbing a grade? Am I wrong?? Am I doing more harm than good? What is max rpm for these motors? TIA

 

You should not pull hard at 1400-1500 RPM, that's how I slipped my lockup clutch.

Your Cummins may be able to do it, but the EGT will be high and the tranny will be under more stress.

Pull (especially if you are running a Smarty) at about 2200 RPM and your TC will hold up better, you'll have better throttle response and your EGT will be lower.

When I'm in the mountains, and theat's a lot, I use Tow/Haul and the lockup switch a lot. When I'm in the slower sections I use 2nd and lockup.

Don't be afraid to add a few revs.

 

Yeap, your RPM's are low for pulling a load. Try to stay up around 1800-2100. Your 3rd gear RPM was at a good level at your speed. The lower RPM with auto will just eat up the stock TC clutch. That is what was shuddering.

 

Thanks guys,kinda figured I was lugging too much.What is this lock up switch? So you can lock up the TC when ever you want? And how easy is it to install? I think that would be a great thing to have as I feel the TC is locking way to quickly

 

Before you think about a tc lock up switch do yourself a favor and get gauges, egt,boost and trans temp. When you were lugging the engine towing your egt's where probably around 1200-1350F. These motors have 24 valves which move more air thru the head and higher rpms make them work, cooler egts. Till you get gauges hit the overdrive off button, on grades hauling the trailer. Don't be worried about pushing 2200-2800 rpms hauling up a grade.

 

1900 RPM is a good cruising RPM with a moderate to heavy load. If it's a light (sub-5000#) load, I would pull at any RPM.

I feel comfortable running any RPM up to redline. Max HP occurs around the mid-2500's, so that's what I would shoot for pulling a load uphill.

 

Don't be afraid of RPM.

2000-2200 is NOTHING for a Cummins.

They'll run at 3000 for years.

 

I agree. My truck has 4.10 and it seems to settle into 1900rpm while towing a travel trailer. It is 64mph at 1900rpm. It will keep that 64mph up hills with no issues at all. Glad to know I could run at 2100-2200 all day if I needed to though.
Its a good truck.

 

I also like 1900 rpm. That is with 4.10 gears and near 35 inch tires.