In search of horsepower and big-time TORQUE

[John Chance]

I continue to see ads for Motorhomes saying they have 500 horsepower or more....I have also been passed by a few large motorhomes like I am standing still....



I come from a long line of gearheads in my family who have always "souped up" their ride for more performance...



I do not want to make my Skoolie a hotrod, nor do I want to go over 70 mph on the freeways, but I do LOVE the feel of at least 500 pound-feet of torque, and the ease of acceleration that kind of torque provides. Does anyone have a Skoolie with a high performance gas-powered engine, and if so, what comments and/or recommendations can you make for someone to follow?

[Steve]

http://www.cummins.com/na/pages/en/p...ingsschool.cfm



Buses with the Cummins ISB 275 have 275 HP but an incredible 660 lb-ft of torque



http://www.cummins.com/na/pdf/en/pro...et/3885388.pdf



The engine is used in school buses, rvs, and fire trucks.

[EldoMike]

Can't remember who but somebody has been using big block Caddy engines in buses....makes a lot of torque...



EldoMike

[Rainforest]

Many of the standard V-8 bus engines have plenty of torque stock. These are heavy duty engine that do not rev very high with 3500 being tops. The easiest way to grab more torque is with camshaft mods. Find a shop that does the grinding and talk with them.

[Steve]

Or if you have an old International like you and me the parts you need can be found from Scout enthusiasts.

[lapeer20m]

as you increase the horsepower of an engine, you reduce the reliability.



I'd rather have a slower more reliable bus. But that's just me.





A BIG truck diesel would be a fine idea for both tons of power and reliability, but they cost big $$$



WE have a firetruck with 3,500 gallons of water, (about 30 thousand pounds of water) and it'll blow by my bus like i was standing still. Not sure which engine is in it for sure. I know its it's a cummings inline 6.......someone said it's an 11 liter.

[frank-id]

There are some ideas about engines that is very difficult understand or Swallow.

as you increase the horsepower of an engine, you reduce the reliability..

hahahhahhahhhahahhaha. Now that is a crock. Some people must have never been to a race. There are many many races and power contests that would easily contradict that statement. There is not a driving person alive, who would not want lots and lots of power. In some cases, engines with lots of power last 5 times as long as a low power engine. A low power engine is always working at the hardest to do any work. A hi-power engine uses power as needed. Hi power can be many things to many people and loads. A corvette with 500 HP is really fun, and a corvette with 300 HP is fun to drive, but not the same. Yep, I do have 3. About all the buses I have owned, I have changed engines and added more HP. Yep, I have 7. My Crown is getting a 375 HP, BC4, Cummins and the 220 HP Cummins is being removed. There is NO substitution for HP and cubic inches. Any changes to and engine for more power is relative to money and Talent. And those little bitty 4 cylinder Offy engine at the Indianapolis 300 race make about 1600 HP at 10,000 RPM for a long time. The engines are about $225,000... Power limitations are mostly caused by lack of funds...

[mightybus]

There is a thread in the coach section that describes a 675 hp Cummins. Vroom, Vroom.

[nevrenufhp]

Stuff the biggest diesel engine you can fit in there. Depending on the bus you have, try to keep it above 7 litres for good thrust. It may not actually be a hotrod, but will feel like one after coming a stock one.

[DEPierce]

Originally Posted by frank-id

There is not a driving person There are some ideas about engines that is very difficult understand or Swallow.

as you increase the horsepower of an engine, you reduce the reliability..

hahahhahhahhhahahhaha. Now that is a crock. Some people must have never been to a race. There are many many races and power contests that would easily contradict that statement. , who would not want lots and lots of power.

Sorry dude...
Driving person


There are some ideas about engines that is very difficult understand or Swallow.

as you increase the horsepower of an engine, you reduce the reliability..

[cadillackid]

Originally Posted by DEPierce

Sorry dude...
Driving person


There are some ideas about engines that is very difficult understand or Swallow.

as you increase the horsepower of an engine, you reduce the reliability..

I always love the racing analogy.. I used to rebuild my drag car engine each season.. I doint want to rebuild my bus engine each season.. that said I do soup the engines up some anyway

[CHEESE_WAGON]

Be aware that all that power means nothing if the trans and differential cannot handle it.

[sportyrick]

If your stuck with gas then cubic inches is the only way to go fast, big block chevy in the 600 cubic inch area should set you back in your seat.

[CHEESE_WAGON]

Originally Posted by sportyrick

If your stuck with gas then cubic inches is the only way to go fast, big block chevy in the 600 cubic inch area should set you back in your seat.

Or a late-model Ford 6.8L V10. Lots of work to swap though.

[BeNimble]

I posted a link to that turbo ford v10 dyno run, at just 6psi of boost, 6psi is not much of a strain, it helps to have 10 cylinders to distribute the load. here found it again: so 425hp and 750 torques, that kicks diesel butt.
I actually have a supercharger for my v10 truck.

https://www.youtube.com/watch?v=37H9dq4FTmM

[flattracker]

I learned during the process of getting the engine replaced in my Crown that the biggest difference between a 300 HP Cummins and a 400 HP Cummins is the fuel pump. The original fuel pump from the Big Cam III that came in the bus was re-used with the 400 HP Big Cam I. I had a local diesel shop in Klamath falls rebuild and re-calibrate the pump for 400 HP. Before I had the gear ratio changed in the bus, it was a rocket ship, but ran out of RPMs at 63 MPH. (stock gearing) when I brought the bus home from Salinas Ca (before any engine problems) the Crown would easily go 70 MPH and I figured out the engine probably was doing about 2400 RPMs at that speed which is 300 past redline. For raw torque a Diesel is king. A 7.3L Power Stroke has great torque and producing extra HP is a matter of better exhaust and tuning with a plugin computer to change the firmware of the computer that run the engine. The Cummins Big Cam I is rated at 1250 ft/lbs of torque. Re-using the external parts from the Big Cam III gave the replacement Big Cam I extra HP because of the improved exhaust manifold and improved turbo.
I will not be making any further changes to the engine because more torque would exceed the ratings of the Allison HT740. I think only Crowns ever used the Cummins Big Cam engine, but the approach may work for other engines.

All the above said, the main reason I now have two Crowns is because the first one was inadequate on hills, overpasses, etc. The HP problem is solved.

[Iceni John]

Or buy a mid-engine 35-foot Crown with a 14-liter Cummins 855: stock was 290 HP, but there are plenty of Crown owners who have 350 HP or more in their buses, and well over 1000 lb/ft of torque. With a Road Ranger overdrive 10-speed and a 3.9 differential you've got a bus that will effortlessly cruise all day long at 80 MPH, and will climb long 6% grades in top or 9th without breaking a sweat. Don't mess about with little pickup truck engines - if you want the real deal, a Crown's the way to go!

John

Oops, looks like someone with such a bus has already chimed in.