Community Forums

Monaco Dave · 03-29-2020, 07:13 AM

Good morning,
I would like to hear from the owners of Class A's running around the country with smaller Cummins, how about that 5.9? How about that 6.7? I am looking for my next rig. What I can say from my perspective is that the 8.3 seems to be about right in my 40 foot Monaco, however, my only concern regarding power is that it can maintain highway speeds pulling my aluminum body f150 and that it can get to the top of the mountains without overheating. Regarding running across flat ground, I like to keep it rolling, seldom under 65, good clear roads, sometimes 75... Thoughts and opinions please

Thanks,
Soon to be, NOT Monaco Dave, by the way, how will I change that moniker? Can't seem to find a way to edit that?

Ivylog · 03-29-2020, 08:10 AM

Do not use the HP #s for the little Cummins, use the torque #s instead and then compare those #s to the 8.3/8.9 engines. Yes, the 5.9/6.7 is a great little engine but not in a 40’ MH.

Damion · 03-29-2020, 08:40 AM

I'm more than pleased with my stock 8.3! Last year on the way to Alaska, did the Sea to Sky Hwy, 13% grades. 38' coach and toad total 32,000lbs. Just came home from Texas mostly 70 MPH, use the cruise all the time! It wants to run 80 if you let it!

Bob_C · 03-29-2020, 08:41 AM

Go to your user cp.....edit your signature

NevadaNick · 03-29-2020, 09:41 AM

We had a Tiffin Red 38qra with 6.7 Cummins and pulled a GMC crewcab pickup. It did fine on the flat or rolling hills and i drove the speed limit which at times was 75. It was relatively slow on some hills, not bad on others, 30-35 mph being the slowest it pulled some hills.

Mr_D · 03-29-2020, 09:53 AM

Quote:

Originally Posted by bob caldwell

Go to your user cp.....edit your signature

He wants to change his user ID. To do that takes a moderator.
OP: when ready to change contact a moderator so they can help you.

cvd · 03-29-2020, 09:57 AM

The 5.9 ISB is a great engine, for moderate sized RV's. I have a 275 hp/600 ft lb version (1999).* It moves my 21,000 lb coach very well, even when towing 6,000 lbs. I wouldn't expect it to do well pushing over 30,000 lbs.

Dutch Star Don · 03-29-2020, 10:33 AM

You'll never hear anyone say they have too much power, so go as large as you can find. Certainly people like what they have, they have to. My coach has the ISL/L9, but could really use the small ISX for better hill climbing.

dirt40 · 03-29-2020, 08:11 PM

We have the 6.7 in ours at 350hp. We pull a 10k trailer and while it does it ok I would get a bigger motor and more horses next time. Would like to see if we could safely upgrade the tune on it.

winniman · 03-29-2020, 08:23 PM

I have the 275 hp 5.9 in a 38 ft coach. I pull a car behind it. It has enough power for me. I get 11 to 12 plus mpg. My friend and his wife have the 300 hp 5.9 in their 40 ft coach. He pulls a full size eco diesel behind it. I have travelled all over the continent with them. He is getting similar mileage, although mine is slightly better. Is it a monster for power. Neither is, but I can say it has far more power than my previous gasser. Both rvs weight in the 26 to 27k gross. I wouldn't want the smaller engine in an rv much bigger. Im thinking of getting a different rv, but Im sure going to miss the mileage if my next one gets 7 to 8 mpg.

SuperGewl · 03-30-2020, 01:14 AM

Here is information you really need. No matter what engine you get, you need the Allison 3000 transmission with it. So yes, this will limit you on small an engine, HP you will get. With any of the Allison 2000 series transmissions you can only tow about 5klbs even if the MFG puts a 10klbs hitch on it. Your truck weighs more than 5klbs so go for the bigger transmission and bigger engine.
The 5.9 ltr and 6.7ltr are great engines but when coupled with the lesser transmission you will not like it compared to what you had. Besides if you are running a 38 footer or larger you want the combination to actually run.
Now as far as the speeds you like to run, WHY, personally its not safe and takes away from the trip. You miss so much by being in such a hurry.

UTTransplant · 03-30-2020, 09:15 AM

We had a 6.7 Cummins, the Allison 3000 transmission. 360 HP on a 40’ exterior rig, and we tow a Grand a Cherokee at 5300 pounds or so. Rig max weight is 32,000 pounds. I generally drive at 62-64 because that is the sweet spot for my rig (sixth gear and 1600 rpm) for economy. While we live in the flats, we travel for months at a time in western mountains, and this baby just keeps climbing. We do end up in third gear and 35 mph sometimes, but I still manage to pass semis without pushing too hard. Note that many rigs our length are set up with a heavier frame, so max weight is an important item in the calculation.

RunningHard · 03-30-2020, 04:44 PM

I have a 5.9 in my 07 36’ Journey producing 300hp and I believe 600’ pounds of Tq. Have had zero complaints driving it and pulling a trailer or toad here in NW. I may not be the first to top of mountains, but not even close to last.

Sundancer268 · 03-31-2020, 02:27 PM

I have never overheated my 5.9 230 HP 12 valve. I have never gone west of the Mississippi, though we have toured the Eastern States and I have never found a highway we could not climb. Might be 20 MPH but the Engine and Transmission temps barely climb above the normal 180-200 degree range.