rpm when towing

bbaker2001 wrote:
So running in TH will change gears automatically and downshift for me?

My gasser ran about 3500 going uphill. So 2000 for a diesel is not a problem going uphill. I dont think I could get it to 2000 on straight ground.
When cruising at 60 it is so quiet, I dont want to lug if, but don't know how to tell

Your tach is your friend. If you enjoy driving like I do, shift as you see fit. I have eyes, the computer can't see the road conditions ahead of us.

bbaker2001 wrote:
So running in TH will change gears automatically and downshift for me?

My gasser ran about 3500 going uphill. So 2000 for a diesel is not a problem going uphill. I dont think I could get it to 2000 on straight ground.
When cruising at 60 it is so quiet, I dont want to lug if, but don't know how to tell

Yes it will do all of that and then some. All modern engine auto tranny combo's will not lug. It's impossible. It knows how much your pulling and what kind of strain is on the engine. It's all programed into the computer. You're along for the ride; just enjoy it.

One more time. Put it into drive; put your TH on and drive.

The computer really should do just fine but here is a torque and power curve that I drew that is likely pretty accurate. From it you can see the importance of having the rpm above 2200 when you want maximum power.

Cummins says you are lugging an engine when you can no longer accelerate. If you have a manual trans I would avoid getting anywhere close to lugging - reagardless of RPM.

Me Again wrote:

Turtle n Peeps wrote:
Put the thing in TH and drive. Forget about shifting and trying to out guess a computer.

And if it is hunting between gears, then lock it in the lower one. I lock out 6 gear when towing a 16K 5th wheel. It will drop of 4th on mountain passes. RPM go to 2100-2200 if I remember correctly.

It is at 1750 at just over 60.

Love it.

Chris

T&P and MeAgain are right, regardless of automatic transmission. You don't have to do anything special with the 68RFE. It might not be as stout as the Aisin, but it is highly reliable at stock power levels.

eHoefler wrote:
The Cummins is happiest between 1800 and 2100. Pulling our 18000 ish fifthwheel, will only go above 2300 on extremely hard pulls.

this

The Cummins is happiest between 1800 and 2100. Pulling our 18000 ish fifthwheel, will only go above 2300 on extremely hard pulls.

every truck has a sweet spot for pulling small and medium hills - my truck always needed to be above 2200rpm for any decent size hill, so keep downshifting till its above that sweet spot and not working your truck overly hard. in mine, a little tip of the throttle right before the hill would bring it down a gear and be right in the meat of the powerband. I was running the 3.31 gears - I'm sure your ram with the 3.42 gears would be similar.

Sounds like what I have been doing. The 68 shifts very easy, it is a towing beast.
I can actually pass going uphill, never did that with my old 5.3
Thanks

Mine slows a bit going uphill also but only about 4-5mph then it downshifts. Either way your not going to hurt it by downshifting, if you feel its starting to pull hard or lug a bit then its time to downshift. If I'm in a hilly area sometimes I'll drop it into 5th and leave it there until things level out. I also tow in TH mode, full engine brake and with cruise set. My tow RPM at 65mph is around 1800-1900, 5th gear doesn't increase it much.