horsepower definition?????

[chopstick1981]

I've have been reading that horsepower is not measured but is calculated from torque... (torque * RPM)/5252= horsepower. For the most part this seems to be the case, but look at just about any rotary engine dyno and this formula doesn't make any sense at all, because if this formula is true then horsepower and torque will have to be the same at 5252 RPMs. Just wondering if anyone could shed some light on this for me?

[ales]

I think you misunderstood some dyno charts. It will still be the same for piston or rotary (or any other) engine - torque and hp will be the same at 5252 RPM, that's why you see the two graph cross at that point.

Example 1

Example 2

[chopstick1981]

i know its the same rotary vs. piston, but i've seen dynos done on rotary engines where the horsepower curve never even comes close to crossing the torque curve, for example check out the rx-7 dyno at this link, at 5252RPMs hp=225, tq=125
http://www.importreview.com/d_mazda.html

[ales]

That's not RPM, that's speed.

[454Casull]

Originally Posted by chopstick1981

i know its the same rotary vs. piston, but i've seen dynos done on rotary engines where the horsepower curve never even comes close to crossing the torque curve, for example check out the rx-7 dyno at this link, at 5252RPMs hp=225, tq=125
http://www.importreview.com/d_mazda.html

ales is right. There's no mention of RPM anywhere.