Diesel engine power

DP's like gassers are not set up to run a 1/4 mile and be at the top of the time trials. My BIL has a 300 HP Cat in a 39 footer, he slows down on long steep hills, but I also do with 350 HP. A Buddy has a 500 HP DP, he also slows down. None of them lug, they will downshift on their own. I guess the questions is, will it be the slowest on the hill, no, will it be the fastest, no, it will be somewhere between the slowest and the fastest.

The answer could be yes or no, how much does the motorhome weigh?

We have a 42 ft. motorhome with a 425 Cummins, weigh just over 40,000 lbs. and we go slow up steep inclines. We always make it over. Our Cummins has 1,200 lb. ft. of torque.

Our new coach will weigh 54,000 lbs, 500 hp Volvo with 1,750 lb. ft. of torque. On the test drive, I did slow on a long grade but not as slow as our current coach. Torque is what moves a diesel.

MM.

Actually HP alone does not answer the question.

There are Cummins B's with 300 HP and 6XX lb-ft torque
There are Cat 3126's with 300 HP and 860 lb-ft torque
There are Cummins C's with 300 HP and 960 lb-ft of torque

They are NOT the same.

The other part of the equation is loaded coach weight with toad.

Depends on your definition of "lug down"

Hpymils wrote:
Is a 300hp diesel sufficient for a 36/37 foot motor home? Will a 300hp lug down on hills?

How fast you go up a hill is solely a function of the HP at the rear wheels and the weight of the motorhome.

My C7 Cat doesn't like to shift down until about 1600 rpms. I don't know if you would call that lugging.

There are many 36 foot coaches with 300 hp diesel engines. 36' diesel coaches probably will weigh around 27K lbs. So I would say yes it is plenty power to move that much weight up hills.

But one thing you have to learn when driving those coaches is to always keep an eye on the tachometer and if it starts to lug down, do not hesitate to shift to a lower gear and keep a certain rpm.

Hpymils wrote:
Is a 300hp diesel sufficient for a 36/37 foot motor home? Will a 300hp lug down on hills?

depends on the Transmission & RearEnd gearing.
IMO more (hp, tq & transmission) is better !

Hpymils wrote:
Is a 300hp diesel sufficient for a 36/37 foot motor home? Will a 300hp lug down on hills?

Compared to what? If you compare it to a gas V-!0 with 362 HP that weights 16,000 lbs and the 300 hp DP weighs 30,000 lbs I would say it will lug (be much slower on a hills).

wolfe10 wrote:
Actually HP alone does not answer the question.

There are Cummins B's with 300 HP and 6XX lb-ft torque
There are Cat 3126's with 300 HP and 860 lb-ft torque
There are Cummins C's with 300 HP and 960 lb-ft of torque

They are NOT the same.

The other part of the equation is loaded coach weight with toad.

The torque/HP question arises periodically. My question is: do all of these engines produce rated torque at the typical 1,600 RPM? What is the difference in the torque/RPM curves?