Diesel Pusher Engine Recommendation

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Larry N. said:
Whether 525+ is necessary depends a lot on weight -- my 2007 Beaver with 525 HP isn't all that sprightly, but it's 42,000 empty, w/50,000 lb max for the coach. It needs that 525.

I think our motorhomes are built on similar RR10 chassis, Larry. I'd bet that the difference in needing 400 hp or 525 hp is only in our minds. Save me a spot when you get there, I'll be 10 minutes behind you because I had to drop one more gear.

Ken
 
Which model/length, Ken, and what is your max weight (GVWR)? Mine's 50,000. And do you have a tag axle? I'll bet your Roadmaster chassis is a tad smaller/lighter, which can make a big difference.

I'd bet that the difference in needing 400 hp or 525 hp is only in our minds.

I'd expect it's not -- I've been a couple of places in Southwest Colorado where I was a tad under 30 mph, and wouldn't have bet I could accelerate to 10 mph (or at all) if I'd had to stop.
 
Larry, 43' Contessa w/tag. GVWR 44,600. You got my by 5,560 pounds of potential capacity. (your factory GVWR is 50,160) So you're sure you need 25%+ more horsepower for potentially (assuming you loaded your rig to the maximum allowed weight) 8% more weight. That's interesting.

Ken
 
I don't know how yours performs, Ken, so I can't comment on (12%, actually) more weight but I'd hate to have less performance, especially in the mountains. In Illinois it wouldn't be a problem at all to have less power, but on a grade in excess of 6% at 8,000 plus feet (near Wolf Creek Pass, for one spot) struggling to maintain 25-30 mph towing a Jeep Wrangler, isn't my idea of overpowered.

In any case, it is what it is.
 
Gary RV Roamer said:
...
If you think you may want to tow something that weighs 5000 lbs or more, make sure the rigs you consider have adequate tow capacity. Most gas-powered chassis are limited to 5000 or less, and some diesels may also be in the 4000-6000 range (but 10,000 or better is more typical of a diesel pusher).

It was already touched on once, but worth re-mentioning with the diesel towing statement.  Do not focus so much on the engine, that the transmission is overlooked if you're looking at towing over 5,000#.  I know the Allison 2500 is limited to 5,000# towing, and I believe that all of the 2xxx series is as well.
 
Thanks again to everyone who commented.  With regards to engine changes I'm seeing a pretty open playing field up until the EPA regs started kicking in in 2007.  That is good to know as I will be looking in the 2000 - 2005 range.  Regards
 
:)Regarding Cat C7 vs Cummins ISC 330HP motors - Cat specs say 7.2 liter (439 cu) the Cummins specs say 8.3 liter (506 ish cu - Obviously the Cummins is the bigger engine, so how is the Cat able to rate the same horsepower as the Cummins and is there a big difference is torque ratings between the two engines. 
 
Cummins ISC ? 260-350 hp; 660-1050 lb-ft torque

Cat C-7      210-300 Hp    520-860 lb-ft torque

On both engines it all varies by installed options.
 
Horsepower is the product of torque x RPMs, so in general the smaller engine with lower torque has to operate at higher rpms to yield a similar amount of horsepower. Other factors, e.g. valve timing and turbo boost affect just how much torque is available at a given RPM, thus adjusting the "power curve" (torque & horsepower vs rpm) a bit one way or the other.

In the RV configuration, the C7 is rated for 860 lb-ft of torque while the ISC is rated at 1050.
 
Ned said:
Engine should not a major consideration when choosing a motorhome, but if you want a rule of thumb look for at least 1hp/100# of GCVW.  There are more important things to look at like floor plan, condition (if used), price, amenities, and to some extent the chassis.  Satisfy yourself with those items and don't worry about the engine as it won't be an option.  If buying new, Cummins will be the overwhelming make since Cat left the on road engine business.  MPG isn't a factor of the engine but mostly by your driving technique and, to a lesser extent, the GVW.

This is NOT so!  I have a Tiffin Phaeton '08 360 HP, and you are good up to 2010 before the need for DEF is needed.
 
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