"HP is just a calculation from tourqe" :confused: :confused: :confused: I think, U are wrong now.... I dynoed my ST4S just some month ago and those HP curve(chart) and TORQUE curve(chart) are totally different !!!! I cant imagine, HOW U can "ONLY COUNT" that???? If U have very good explanation, surely then i can accept Your taughts.... :thumbup: Anyway to me, "torque" and "hp" are totally different things.... :thumbup: Anyway there can be misunderstood with metric and US units with those numbers...

Horsepower (using English units) is defined as (Torque * rpm)/5252. There isn't any dyno in the world that I know of that actually measures horsepower, it's derived from the torque curve. Unless it's an inertia dyno, but even then horsepower is derived.

Torque is a force. HP is simply the rate at which that force can be applied. Switching to metric units only changes the denominator of the equation. If you google "equation for HP" you will probably come up with the derivation of the formula that will lead you through the steps to get to 5252.

Sidenote: On any US dyno curve that measures HP and ft*lb torque, the curves will cross at 5252rpm. Many dyno charts will show torque and HP on different scales so it doesn't look like they cross there, but they do, by definition. If not, someone is playing games with one of the curves.

"Unless it's an inertia dyno, but even then horsepower is derived" ??? My ST4S was in INERTIA dyno. But i must look more those my dyno charts... very intresting, but surely my "english" is quite bad also... :laugh: