DP Horsepower

Nomadac wrote:
I once read or heard a guide of 1 HP for each 100 lbs. Gross Wt. of MH.

Yes, that is the general rule-of-thumb. Less than that means the coach will be slooow in the mountains, but will eventually get there.

DanTheRVMan wrote:

Mr.Mark wrote:
As I've mentioned before in the past, we go slow up steep inclines. I can pass some truckers but most motorhomes pass us. We have the 425 hp Cummins with 1,200 lbs. ft. of torque. We weight just a hair over 40,000 lbs.

I just let the cruise take care of the speed but if I get a running start, I can pass a lot of vehicles. One problem is, if we get caught behind a very slow truck, it's hard to pick up speed to get around them while climbing the hill. I'm not trying to race up but I thought that we would go up faster.

The new coach I'm thinking about has 500 hp w/ 1,750 lb. ft. of torque and weighs over 50,000 lbs. I may be in the same situation.

MM.

http://www.prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

weight/hp or weight/(torque x rpm)

increase weight - speed decreases
increase torque (thereby increasing HP) - speed increases
increase rpm - speed increases
increase hp - speed increases

hp is simply a mathematical substitute for torque x rpm BOTH of which increase speed up hill.

On Edit - if your coach is heavy try to enjoy the view like Mark:B

Anyway, the poster who used the leg press analogy hit the nail on the head. Sometimes its unfortunate that torque gets brought up.

For your specific question, yes... 260hp is adequate as it will get you where you are going. Sometimes adequate is an adjective that can be relative though.

Without knowing the gearing or year of the V10 you referenced, its hard to estimate the amount of torque delivered to the wheels to say how your overall experience with the DP will be comparatively but all years of the V10 put out more than 260hp so your experience with top speed on grades will be worse. That is of course assuming that you were getting all the power possible out of your V10 by letting it rev. If not, you may have a more pleasant experience with the DP as it will appear to not be working as hard to keep a similar speed on an incline.

Mr.Mark wrote:
As I've mentioned before in the past, we go slow up steep inclines. I can pass some truckers but most motorhomes pass us. We have the 425 hp Cummins with 1,200 lbs. ft. of torque. We weight just a hair over 40,000 lbs.

I just let the cruise take care of the speed but if I get a running start, I can pass a lot of vehicles. One problem is, if we get caught behind a very slow truck, it's hard to pick up speed to get around them while climbing the hill. I'm not trying to race up but I thought that we would go up faster.

The new coach I'm thinking about has 500 hp w/ 1,750 lb. ft. of torque and weighs over 50,000 lbs. I may be in the same situation.

MM.

http://www.prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

weight/hp or weight/(torque x rpm)

increase weight - speed decreases
increase torque - speed increases
increase rpm - speed increases
increase hp - speed increases

hp is simply a mathematical substitute for torque x rpm BOTH of which increase speed up hill.

On Edit - if your coach is heavy try to enjoy the view like Mark:B

Mr.Mark wrote:
As I've mentioned before in the past, we go slow up steep inclines. I can pass some truckers but most motorhomes pass us. We have the 425 hp Cummins with 1,200 lbs. ft. of torque. We weight just a hair over 40,000 lbs.

I just let the cruise take care of the speed but if I get a running start, I can pass a lot of vehicles. One problem is, if we get caught behind a very slow truck, it's hard to pick up speed to get around them while climbing the hill. I'm not trying to race up but I thought that we would go up faster.

The new coach I'm thinking about has 500 hp w/ 1,750 lb. ft. of torque and weighs over 50,000 lbs. I may be in the same situation.

MM.

X2 for my 2 DPs. I suspect your right about the new rig.

Now if you got a 30K lb rig with 600HP then you would have a rocket ship.

As I've mentioned before in the past, we go slow up steep inclines. I can pass some truckers but most motorhomes pass us. We have the 425 hp Cummins with 1,200 lbs. ft. of torque. We weight just a hair over 40,000 lbs.

I just let the cruise take care of the speed but if I get a running start, I can pass a lot of vehicles. One problem is, if we get caught behind a very slow truck, it's hard to pick up speed to get around them while climbing the hill. I'm not trying to race up but I thought that we would go up faster.

The new coach I'm thinking about has 500 hp w/ 1,750 lb. ft. of torque and weighs over 50,000 lbs. I may be in the same situation.

MM.

Passin Thru wrote:
Now for your answer. Yes the 260 Cummins will do it. You can turn a 260 up to 300 or even 350 but I'd have a pyrometer and vacuum gage and be careful as it will melt pistons. What is your hurry? You should be retired and where do you have to be? Also when someone writes a diatribe of gobbelty-good about torq Hp etc etc etc, dont add it to your reply. No one cares. Not me anyway, I could read all that on Google but I'm already a mechanic.

Yep, you can do that, but you better have a transmission that can handle that torque, and most who have those little engines also have little Allisons that will not handle it. Now I'd love to have a 13 speed Roadranger behind my Cummins 6bt 5.9, but I have to live with the Allison MT643 which has a net input of 250 hp and 640 ft lbs of torque. So I'm pretty much stuck (and happy) right where I'm at!

Nomadac wrote:
I once read or heard a guide of 1 HP for each 100 lbs. Gross Wt. of MH.

I'm on my second rig in that vicinity. Both would drag down to 45MPH on a 5-6% grade. Only you can decide if that meets your requirements.

Sure I'd sometimes like a rocket ship but there are a lot of other considerations.

All the Jibber-Jabber. I had a Cat 3406 E with 1450 ft lb torque and 500 Hp. It would pull 80K at a decent rate anywhere in the US. Now for your answer. Yes the 260 Cummins will do it. You can turn a 260 up to 300 or even 350 but I'd have a pyrometer and vacuum gage and be careful as it will melt pistons. What is your hurry? You should be retired and where do you have to be? Also when someone writes a diatribe of gobbelty-good about torq Hp etc etc etc, dont add it to your reply. No one cares. Not me anyway, I could read all that on Google but I'm already a mechanic.

My 'little' V10 gets a steady 8+ mpg and I've yet to go less than 50 mph on any of our western passes. $2.73 a gal beats ANY diesel price per mile, and I pass those big guys going up hill. It's HP/lb folks-that's all folks!

Distilled down a HP is a HP-- be it from a gas or diesel.

The BIG difference is that the diesel can generate that HP at a much lower and more economic RPM with less shifting.

Said another way, I can climb most grades around 1600 RPM (peak torque is 1,440 RPM), probably 1/2 the RPM a gasoline engine would need to generate that HP.