When is my Cummins the happiest?

[Durb]

I have a 2004.5 RAM with the 5.9L and the 4 speed automatic. I tow a 10,000# trailer for 18,000# combined. I find the transmission has awkward ratios at 55-60 MPH:

At 55MPH - In drive, 1,500 RPM, Exhaust gas temperature in the 800's
At 55 MPH - in Tow/Haul, 2,200 RPM, EGT in the 600's

At 60 MPH - In drive, 1,700 RPM, Exhaust gas temperature in the 800's
At 60 MPH - In Tow/Haul, 2,400 RPM, EGT in the 600's

What gear should I be driving in while towing at these speeds? It seems like it is lugging when in OD. I am thinking in terms of engine longevity, transmission longevity, fuel economy. The truck is perfectly content at 65 MPH in OD.

[DirtyOil]

My Ram is happiest when not towing Fish's Ford... :B

[john_bet]

I have the same truck with a 3.73 rearend. I tow a 12K 5th. I put the selector in "D" and drive. I have towed in all kinds of traffic and all kinds of roads including some in your state. On Interstates it is 1800 rpm at 65 mph. I let trans do it's thing. Very seldom touch the T/H button.

[transamz9]

wilber1 wrote:

transamz9 wrote:

wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.

That's odd. No wonder they only did it for a year.

Yeah,it's kind of stupid if you ask me. What just as stupid is in 06 when they started offering both options they put it on the same switch, the button on the end of the shifter. Push it once for tow/haul. Push it a second time to lock out OD. Pusher it a third time to go back to normal. There are times on the back roads that I wish I could easily lock out OD when running 35 - 50. I can lock it out on my tuner but is not as easy as pushing one button but you get the point.

[wilber1]

transamz9 wrote:

wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.

That's odd. No wonder they only did it for a year.

[transamz9]

wilber1 wrote:
Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

On the first 48's 04.5-05 the torque convertor will only lock in OD (4th) when the tow/haul is off. With tow /haul on it will lock in 3rd and 4th. It will also lock in 2nd if you put the gear selector in "2". Tow haul was the only option on the 48's in 04.5-05. In 06 they started offering tow/haul and also OD lock out.

[wilber1]

Yup. Peak torque at 1600 RPM so 1700 RPM would not be lugging, you just make less HP than at 1900 RPM. Don't know about the 48RE but my 47RE did not have tow haul and would not run in 4th with the torque converter unlocked.

[transferred]

KD4UPL wrote:
What RPM is peak torque? Probably around 1,900 or so. That's where you should be running it.

No, peak torque is at 1,600rpm in the Cummins 600 and 610.

edit- added both 600 and 610 variants

[transamz9]

Durb wrote:
Thanks for the feedback. Sounds like revving over lugging is preferable. I would like to drive 65 (1,900 RPM) all the time but sometimes traffic won't let me. Last trip I followed a friend with a Motor Home and apparently his sweet spot was 59-60.

Your truck is happiest when the torque convertor is locked. This happens the most in tow haul mode. 😉

[DakotaDad]

Edited in the spirit of discretion...

[Durb]

Thanks for the feedback. Sounds like revving over lugging is preferable. I would like to drive 65 (1,900 RPM) all the time but sometimes traffic won't let me. Last trip I followed a friend with a Motor Home and apparently his sweet spot was 59-60.

[Flashman]

FishOnOne wrote:
My Power Stroke has enough power across it's operating range I simply put it in Drive and that's it. No hunting for gears and no shifting like it's a "built transmission".

Well I drive a 6 speed manual. Something you Ford boys can't do any more. Too bad. The only hunting for gears that goes on is when I want it.

Oh by the way my tranny is a true medium duty tranny is yours?

[transamz9]

FishOnOne wrote:
My Power Stroke has enough power across it's operating range I simply put it in Drive and that's it. No hunting for gears and no shifting like it's a "built transmission".

RAM MAFIA!!!! Oh wait.......

[FishOnOne]

My Power Stroke has enough power across it's operating range I simply put it in Drive and that's it. No hunting for gears and no shifting like it's a "built transmission".

[4x4ord]

I don't worry too much about what my truck likes. I put it in drive and usually drive the speed limit. I seldom use tow/haul and I accelerate gradually. With my 2011 I used tow/haul some but on my 2016 I just turn the exhaust brake on and when I want the engine to hold back I manually select the appropriate gear. If I wanted my truck to be happiest I guess I would use tow/haul, select drive and trust that the engineers knew what they were doing when they programmed things.