How Much Horsepower?

[usbusin]

The subject keeps coming up about how much horsepower does it take to go a certain speed or how much fuel will I consume to go that speed.

Here is an interesting site that lets you calculate how much horsepower is required (at the rear wheels) to go a certain speed.  
http://www.wallaceracing.com/Calculate%20HP%20For%20Speed.php

Once you calculate this you can use the fuel consumption tables for your engine and determine what your fuel mileage will be.  Here is an article by Clarke Echols that will get you started.
http://users.cwnet.com/~thall/clarke_echols.htm

Here's another.
http://www1.eere.energy.gov/cleancities/pdfs/bus_fuel_economy.pdf

A little research on Google or Bing will get you some more interesting info.

Have fun!

GaryD

[Iceni John]

What's the typical Cd of a bus?   I suspect it's about 1.00 for most of ours, especially mine that is slab-fronted with the aerodynamics of a brick privy (unlike older Twinkie-shaped Crowns that are rounded front and rear).   A 1950s Hall-Scott-engined Crown achieved 103 MPH once on a racetrack, but there's no way a bus like mine would come close, even if it were geared high enough.

John  

[chessie4905]

   That doesn't take into account hills or grades. I think you can get a better estimate from other owner's reports. It's hard to lie about your numbers here, as you are going to be called out on unrealistic mpg's. A  fair variation will occur due to heavy foot, and how do you baby a coach on a grade? Get a run for it or let it lose momentum gradually and start holding up traffic. How many on here run their generators off the main fuel tank, skewing their figures? How much total weight do you carry. How much is from trying to fill up all those empty spaces in bays, etc. with everything for convenience, including an spare kitchen sink?

[Emcemv]

6.1mpg on the return to ct from Blytheville. No generator running. Just about what I was expecting. Running no faster than 65mph.

Bruce

[bevans6]

I did the calc, got 160 hp at the rear wheels for 80 sq. Ft, 0.9 CF and 26K lbs.  Sound quite believable to me, that would correspond to maybe 220 at the crank.  For 80 mph it says 325 hp, so add 40 for accessories and 15%  for drive train that would be 416 hp.  I knew I couldn't run 80 anyway, but now I know.

Brian

[HB of CJ]

Wow; FWIW, Crown Supercoaches must be more slick than imagined.  My old 1974 Crown 10-wheeler 40-ft ex-schoolie would max the speedo at an indicated 80-82 mph with just a RTO-910 Roadranger and a non turbo Small Cam 855 inch Cummins rated at only 250 hp.  Thanks again.  HB of CJ (old coot) now-buss-less   Still LOVE this forum!

[wg4t50]

Speed, MPG, weight & HP is always an interesting topic, Can assure you a proper 8V-92 with the RTO910, 3.73 on 11R24.5 will show 100+ on GPS, MPG who cares at that point?
At the other end of the game, my present setup ISM500, 4000R, 3.92, 275/80X22.5 will give you 9 mpg driving reasonable, low 60ish, but that is more nerve racking than the fuel cost at 70ish/7.5 mpg.  Its all the right foot.

[luvrbus]

LOL fall in behind Sonnie Grays Eagle with the 350hp Cat engine and 740 Allison it blows that theory all to hell