how is hp converted?

[S13inyourface]

my friend told me that if a car is rated at like 300 hp, it only puts like 200 to the ground or something...is he right or is it all the same....i have heard like 300hp to the flywheel, and like 325 to the rear tires before....idk just wondering

[Fenvy]

your friend is a foolio! jk

he's talking about flywheel HP to wheel HP... usually a 15% to 20% reduction but certainly not a 33%

[AmoebAssassin]

very generally, if you are converting a manufacturer supplied engine power figure to rwhp, follow:

stated crank hp - (Driveline loss percentage)*stated crank hp

If you have a rwhp number taken from a dyno, solve this equation for crank hp:

crank hp - (driveline loss percentage)*crank hp = rwhp figure

[Toddles82]

he's talking about flywheel HP to wheel HP... usually a 15% to 20% reduction but certainly not a 33%

That's the rule of thumb everyone uses. I've heard 15% for a manual and a hair above 20 for auto-tragics.

so a claimed 100 HP motor actually puts down to the wheels:through a manual - 85 HPthrough an auto - ~78 HP.

This is due to friction loss, thermal inefficiencies and the nature of a combustion engine (includes the two previous reasons as well).

[dfw240_EE]

20% for an auto is standard, but not all drivelines are equal. For example I read in Car and Driver a while back about the Suzuki Verona that it lost about 30% of it's torque in the driveline. If I can dig up the article to confirm, I will and post the reference.

Also I believe AWD loses more HP in the driveline than RWD due to the greater complexity. Then RWD loses more than FWD since FWD has fewer shafts and bearings.

[ILikeMy240sx]

....i have heard like 300hp to the flywheel, and like 325 to the rear tires before....idk just wondering

Did you ever hear of conservation of energy?

from the title of your thread... how is hp converted it sounds more like P=T*RPM...

Anyways please please please read a bit more before posting things... its really annoying to see posts like this when you can just read a bit more and LEARN before you post. Its a common courtesy. You cant expect us to answer every little question you have because you are too lazy to search.

[Toddles82]

Everything Dfw said is true. hehe.

[Dattebayo]

You really want to know the true secret?

The magic fairy inside that metal thing under the hood eats gasoline and farts out HP.

[The 240 kid]

Did you ever hear of conservation of energy?

Yes, but still think of the posibilities. More horsepower to the ground than the engine actually puts out.

[ILikeMy240sx]

hmm I guess you cant really blame him for hoping