rpm when towing

[bbaker2001]

When towing with my ram diesel how do I tell when I should downshift.
it seems to tow so easy, but slows when going uphill
at 60 what should my rpm show.

[VoodooMedicineM]

2005 6.0 ford diesel manual transmission, 2000 rpm is the sweet spot. About 62mph.

[VoodooMedicineM]

2005 6.0 ford diesel manual transmission, 2000 rpm is the sweet spot. About 62mph.

[ShinerBock]

Turtle n Peeps wrote:

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.

As tranzam said, in certain conditions they will lug. When I am towing in the Texas hill country, which is a lot of constant sharp up and down hills, the engine will lug going up some hills. My truck will automatically apply the exhaust brake because it is gaining too much speed going down a hill which will slow down the turbo compressor. If there is an incline immediately after this, then the engine will lug because there is no boost and the trans will not know what to do for a short time until it downshifts. Even my brother 2012 F350 will do this and I would suspect that a Duramax would as well in the same conditions. The only way I have found to combat this when my truck was stock was to lock it into certain gears. After I custom tuned my truck's shift points, this was not an issue.

As far as the OP's rpm question. Lower rpm+high load= high EGT's which means greater chance of engine/turbo damage. Higher rpms with load will generally have less EGT's. I would recommend sooner oil change intervals if you at high rpms for long periods or on a normal basis though.

[transamz9]

Turtle n Peeps wrote:

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 Aisin I have now and the 13' that I had before will lug. I've seen it down to 1100 RPM with my foot on the floor in 3rd gear with the TC locked. It is a rare occurrence but it does it and is aggravating. It does it in the little short rolling "Bumps" that you see a lot of around here. They are short 2-300 yard long 10-12% grades that go up and then break over and go down for 2-300 yards then back up. The computer gets confused going from full power to full exhaust brake back to full power. It's hard to explain but it does. second to third is a big jump especially the the TC locked. I've never had an issue out on the road at highway speeds though.

[4x4ord]

If the rpm drops about 500 it is due to a gear shift. If it only drops about 100 rpm it is likely due to the torque converter locking up. The reduction in noise is either a shift or the cooling fan cutting out.

[bbaker2001]

Wow great info
I noticed when going up a hill, I never reached the point that I could not accelerate it just seemed so quiet. I pressed the minus button, and it already had shifted to 5th, thought I might need to go to 4th, but it kept pulling.
I hear it vo to higher rpm, then goes quiet and the rmp drops. Is that the turbo kicking in

[coolbreeze01]

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.

[Turtle_n_Peeps]

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.

[4x4ord]

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.

[ScottG]

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.

[Bionic_Man]

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.

[Wild_Card]

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

[eHoefler]

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

[alexleblanc]

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.

[bbaker2001]

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