I am looking to upgrade from a gaser to a diesel pusher. The new RV is on the Freightliner XCS chassis using a 340-hp Cummins ISB 6.7L turbo-charged engine. It has an Allison 6-speed autmatic 2100MH transmission. The RV length is 35' 6" with a GCWR of 30,000 lbs and a GVWR of 26,000 lbs. I pull a car on a tow dolly which falls into the spec of the trailer hitch 5,000-lbs drawbar/500-lb.My question; is the 340-hp diesel engine an adequate size engine? I have only had gas engine motorhomes.Thanks for your feedback,Ron

Rule of thumb is 1Hp per 100 lbs,so going by that a 340hp motor is good for 34000 lbs GCWR.

Probably a better Class A Forum question. You can click "Notify Moderator" and have it shifted over there. I have no experience with DP's, but from what I read, it's amazing how many OP's are pleased with the 5.9 Cummins in what I'd think was too large a coach for it.Still, I think the scene from "Smokey and the Bandit" applies. Bandit needs a fast car and his customer hands him a wad of cash. Bandit says "Not fast enough" and gets another handful. "Still not fast enough", another handful...If a lot of your travel is going to involve mountains, your toad is going to be heavy, maybe an option with more HP. And I'm sure a diesel fan would come in with saying, "No, more TORQUE."But from what I read, where I go, what I tow, I think the chassis/engine/transmission you list would be nice.

What is the current equivalent to the 8.3L Cummins? (the 8.3L Cummins 6cta was the larger displacement engine in the same family as the 5.9L 6bt)

The current Cummins 8.3 is the ISC line and typically around 350HP/1000 ft-lb torque in RV use with the EPA 2010 after treatment setup.

Go for it! Have a 36' DP with a CAT 3126 E @330 HP and 860 ft. lbs of torque. I pull a 4,500 lb Nissan XTerra and this rig will climb a flag pole!!!

Diesel pusher engine size | Good Sam Community

11 Replies

mchero
Explorer
May 07, 2014
I just upgraded from an 3.3l mechanical Cummings to a CAT 320HP. Sure miss that Cummins but CAT 320HP plenty for my 39" coach.
12ItSu30a
Explorer
May 07, 2014
My gasser is a F53, 362-hp, 6.8L super duty V10 SEFI Triton.
CA_Traveler
Explorer III
May 04, 2014
More than adequate but it's not a rocket ship. I'd expect 40-45MPH on a sustained 6% grade with that rig and 8 MPG.
thgoodman
Explorer
May 04, 2014
Well, ya' remember the old saying "You can't be too rich or too beautiful"? I would add to that you can't have too much horse power / torque. But, as j-d's reference from Smokey and the Bandit tells us more power will cost you more money.

525 hp, 48,000lbs, 4-5 mpg here. But when I'm pulling a 10 mile, 6% grade on I-5 on the CA/OR border, I wouldn't have it any other way.
Gjac
Explorer III
May 04, 2014
You don't say what your gasser is or what it weighs. If it is a newer Ford or Workhorse and has 340 or 362 hp and weighs 16,000 lbs vs 350 hp and weighs 30,000 lbs you may be disappointed in the performance difference. When folks talk about performance here it is very subjective. If you bought the 6.7 DP first and had nothing to compare to you would probably be happy with it.
keepingthelight
Explorer
May 03, 2014
I have heard good things about the 6.7L. There are programmers that can be added if needed.

http://www.thoroughbreddiesel.com/ts-performance/mp8.htm

Good luck ;)
gswcgi
Explorer
May 03, 2014
Go for it! Have a 36' DP with a CAT 3126 E @330 HP and 860 ft. lbs of torque. I pull a 4,500 lb Nissan XTerra and this rig will climb a flag pole!!!
the_armadillo
Explorer
May 02, 2014
The current Cummins 8.3 is the ISC line and typically around 350HP/1000 ft-lb torque in RV use with the EPA 2010 after treatment setup.
mthockeydad
Explorer
May 02, 2014
What is the current equivalent to the 8.3L Cummins? (the 8.3L Cummins 6cta was the larger displacement engine in the same family as the 5.9L 6bt)
j-d
Explorer II
May 02, 2014
Probably a better Class A Forum question. You can click "Notify Moderator" and have it shifted over there. I have no experience with DP's, but from what I read, it's amazing how many OP's are pleased with the 5.9 Cummins in what I'd think was too large a coach for it.
Still, I think the scene from "Smokey and the Bandit" applies. Bandit needs a fast car and his customer hands him a wad of cash. Bandit says "Not fast enough" and gets another handful. "Still not fast enough", another handful...
If a lot of your travel is going to involve mountains, your toad is going to be heavy, maybe an option with more HP. And I'm sure a diesel fan would come in with saying, "No, more TORQUE."
But from what I read, where I go, what I tow, I think the chassis/engine/transmission you list would be nice.