Considering Diesel A - 275 hp Cummins questions?

[AstroRig57]

After selling our 32' Class-C gasser, and considering whether to go with a TT or Class-A motor home, we've decided on a Class-A and are now working on our "short list"

I thought I wanted another gas rig but, to my surprise, we've found a diesel pusher rig with which we are pretty well enamored. I know, you've probably answered these ad-nauseum, but here's a few questions I have.

The rig were looking at right now is a fairly late model, used, 36' Winnebago on a Freightliner chassis, 26,350 lb GVW. It has a 275hp Cummins Turbo Diesel and Allison transmission. My question is, is that engine powerful enough so a rig that size can even get out of it's own way? I know diesels have different torque characteristics than gas engines but have no idea if the 275hp Cummins would be considered a bit anemic for this rig or not? On steep grades, will we be the slowest thing on the road?

Also, in regard to the cost of fuel, the days of diesel being cheaper than gas are long since past especially in CA with the low sulfer diesel requirements. How does fuel mileage on a diesel pusher compare with that of a comparably sized gasser? Does better mileage offset the higher price of diesel or not?

I won't ask the questions re maintenance costs etc., as I've seen those pretty well covered. Also, this rig will be out at least 2-3 weekends a month so the "can I let it sit" question is a moot point as well.

Thanks

[predawn]

Gjac wrote:
OP: My question is, is that engine powerful enough so a rig that size can even get out of it's own way? I know diesels have different torque characteristics than gas engines but have no idea if the 275hp Cummins would be considered a bit anemic for this rig or not? On steep grades, will we be the slowest thing on the road? This is a good question but it is all relative. Relative to your Class C it will probably be slower up the hills,if you had a 362 HP Ford or a 340 HP Chevy in a chassis that weighed 15,000 lbs. A 275 HP MH that weights 26,000 lbs has a lot less HP to Wt ratio. How much slower? My guess is 30%. You would have to test drive it to see if it is OK to you.

Ok on flat areas. Once you Load that unit up and add a TOAD and it will be a dog on any mountain pass or real hilly areas.its not like it wont work as it will. Just Not for me as its a a dog in my opinion, others will vary.I had a 37ft 325 HP 1000 Lb Torque ISC and it was marginal
NOTE OP said 26000 GVWR not Base weight of vehicle!

[Gjac]

OP: My question is, is that engine powerful enough so a rig that size can even get out of it's own way? I know diesels have different torque characteristics than gas engines but have no idea if the 275hp Cummins would be considered a bit anemic for this rig or not? On steep grades, will we be the slowest thing on the road? This is a good question but it is all relative. Relative to your Class C it will probably be slower up the hills,if you had a 362 HP Ford or a 340 HP Chevy in a chassis that weighed 15,000 lbs. A 275 HP MH that weights 26,000 lbs has a lot less HP to Wt ratio. How much slower? My guess is 30%. You would have to test drive it to see if it is OK to you.

[discovery4us]

I can say from experience that you will be fine with a 5.9 275 HP cummins with a 6 speed Allison. If it is rated at 275hp and 660 torque it should be the 6 speed. If you are still shopping send me a private message and I can give you a lead on a nice unit in Bakersfield that you might want to look at.

[Ivylog]

What year and what engine? Could be a 5.9L ISB or a 8.3l with a big difference in torque.

[hershey]

I have the same engine, but rated at 260 hp, a 2001 Cummins. 36' Expedition. I have nearly 80,000 miles and tow a Suzuki Grand Viagra, 3100 lbs. 47 of the 48 states and overall fuel mileage of 9.22 mpg. We full time and it gets regular care and feeding. I'm not the first to the top of the hill, but I'm the last one at the fuel pump. Its really very adequate for the task. Sweet spot for travel is 62 mph. It will easily cruise at 70 if I'm in a hurry.

[Golden_HVAC]

Considering that you live at 4,500' elevation (or close to it) you need something that is great in the hills, not something that is 'just powerful enough'.

That said, Banks can do wonders to a 275 HP motor to improve the situation. Call them first, with the engine size, RV weight, GVWR, ect. THey probably have a intake manifold and larger turbocharger that will spool up quicker, and improve your HP rating by 50 - 75 HP! At that point, you would also need to improve the cooling capacity to keep using all that HP. Your radiator is probably sized for a 250 HP engine, and will overheat a little when climbing a long grade, but after 10 minutes at full throttle, you will start back down the other side, so no problem undersizing the radiator a little bit. Change the engine to 325 - 350 HP, and you might find it overheats on long grades!

Your transmission will handle the extra HP no problems. Depending on the mileage, you might want to change the transmission fluids, (it should be done every 25,000 miles or so, but most RV owners never consider it needs changing).

Banks is not to far away, in Azusa CA. I had my Banks system factory installed in my year old 1997 Bounder with a 460" gas engine, and I loved the HP improvements. You will be able to try out the new power on I-15 right away, leaving the factory! They might recommend a larger intercooler, turbo, and intake manifolds. This provides more cool air to the engine, and makes it breath much better. Yet it can be expensive, and if you are getting the 275 HP rig for a great price, it will be well worth it to change it to 325 HP rig, and it will be a great selling point!

Good luck with your purchase!

Fred.

[rr2254545]

My 36 has a 360 engine and towing the jeep it gets down to 45 on some hills on the interstate including today on I5 south of Seattle

[predawn]

AstroRig57 wrote:
After selling our 32' Class-C gasser, and considering whether to go with a TT or Class-A motor home, we've decided on a Class-A and are now working on our "short list"

I thought I wanted another gas rig but, to my surprise, we've found a diesel pusher rig with which we are pretty well enamored. I know, you've probably answered these ad-nauseum, but here's a few questions I have.

The rig were looking at right now is a fairly late model, used, 36' Winnebago on a Freightliner chassis, 26,350 lb GVW. It has a 275hp Cummins Turbo Diesel and Allison transmission. My question is, is that engine powerful enough so a rig that size can even get out of it's own way? I know diesels have different torque characteristics than gas engines but have no idea if the 275hp Cummins would be considered a bit anemic for this rig or not? On steep grades, will we be the slowest thing on the road?

Also, in regard to the cost of fuel, the days of diesel being cheaper than gas are long since past especially in CA with the low sulfer diesel requirements. How does fuel mileage on a diesel pusher compare with that of a comparably sized gasser? Does better mileage offset the higher price of diesel or not?

I won't ask the questions re maintenance costs etc., as I've seen those pretty well covered. Also, this rig will be out at least 2-3 weekends a month so the "can I let it sit" question is a moot point as well.

Thanks

low sulphur is North America wide. A 5.9L ISB 275 HP rig is
Ok on flat areas. Once you Load that unit up and add a TOAD and it will be a dog on any mountain pass or real hilly areas.its not like it wont work as it will. Just Not for me as its a a dog in my opinion, others will vary

[Johnny_G1]

Nothing wrong with that rig, have travelled all over North America in our rig, always kept up with the traffic, and good on fuel.

[sonora]

And I would buy a Cummins over a Cat any day.

[Mr_Mark1]

The HP rating is in relation to weight. A 275 hp engine in a 26,350 lb. chassis, is about the right balance that you see in all coaches. Our previous 425 hp engine with 1,200 lb. ft. of torque in a 40,000 chassis was about right. Although it seemed slow on steep inclines, it was a good runner with good fuel mileage.

Our current coach with 500 hp and 1,750 lb. ft. of torque, moves 53,000 lbs. quite well. We slow down on steep inclines but we can go 75 mph all day long in the interstates. I prefer about 60 mph but it's good to know that we could scoot right along if we need to make up some time.

I think your 275 hp will get the job done.

MM.

[Executive45]

For a 36' coach the 275HP will do just fine. Check out the coach well, look at the tire date codes as new tires will cost a bit. Drive it and see how well it does. I think you'll be surprised....Dennis