Horsepower

[U.S.BlueStage2]

How come the horsepower rated by Ford (with the mustang for instance) appears to be less than what most people would say is actually generated at the wheels?

The 2002 GT is rated at 260 "horsepower" by Ford.

It is confusing especially when shopping for a supercharger, some companies claim 130 "horsepower gain" and others, claimng to sell virtually the same product claim only 70 "horsepower" gain.

So, is it, for example, 70 "horsepower" on top of the 260 hp Ford rating to result in a "horsepower" of 320; or is it some other figure?

Any ideas


and then the different acronyms dont help- bhp, sae, rwhp,hp (some are self-evidence others not so)

[dCypher]

when manufacturers refer to just plain ole' 'hp', they are always refering to at-the-crank horsepower. Not rear wheel horsepower (rwhp)

when a power adder company touts 'an added 100 hp', they always mean crank horsepower as well.

there can be in the neighborhood of a 15% hp loss through the transmission from the crank to the wheels, so keep that in mind..

Als remember that enviornemental factors play a huge role when you dyno your car. My car dyno'd in Dallas will almost NEVER give the same rating when dyno'd in Chicago, let alone from one pull to the next. Everything from air temperature, humidity, dew point, and the quality of gas you use can effect your car's horespower.

For example, you can vary a LOT of hp in just using Exxon's gas over Mobil, since not all refining processes are the same. 92 octance from company X will often not run the same as 92 octane from company Y (this is just an example mind you)..

[fast94five-oh]

most stock mustangs dyno between 230 and 235 i think. just fyi

[U.S.BlueStage2]

Welcome to fnsweet, and thanks on the hp, that seems to be the consenus

[knuther]

HP rateings are very hard to think about... Some Over sea's car's for example rate there cars at BHP or brake horse power... then there is Flywheel Hp and RWHP.... its very confusing and takes bout 20 hours to get all in perpective... On adveraged though you can useally take a Flywheel hp and take it times .85 and get the RWHP but not always.... Automatic's take more ponies to run and there equation is around 20% loss... So it would be times .80 for auto's

THis equation goes down however... IF you have a alum flywheel/ lighter clutch/ alum driveshaft.... these things can all contribute to less weight witch brings the equation of 15% drivetrain loss down to about 13% .... Its hard to hit the head right on the nail but you get the idea... Now with mustangs... Remeber that roush... is conservative on there RWHP i think we have seen some people with way more hp then the advertised 360flywheel on the S3, but Saleen is always kind of Padding the numbers u might say... so when they say 360hp they really mean 349 ??? its all kinda of confuseing but after you get the drift of things it will be alot easier...

[KenR]

1 more thing. A S/C takes Hp to run. So when you put 350 to the ground and you figure your numbers for flywheel hp add 25-45 for the HP your S/C is pulling in parasitic HP (from pullies)