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Old 11-29-2012, 09:02 AM   #71641
Knuckle dragger
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Joined: Dec 2009
Location: North Carolina Y'all
Oddometer: 3,127
Originally Posted by Rusty Rocket View Post
Horsepower can be misleading. 2 engines making equal foot-lbs of torque will have different horsepowers if they are acheiving them at different RPM's. The engine making the same torque at the higher RPM will have a higher horsepower. Say a 125 makes 40 ft-lbs torque @ 10,000 rpm and a 650 makes 40 ft-lbs at 6500, the 125 will have more HP> I'd rather have my torque from a lower revving engine so it lasts longer

The old saying (If I remember it correctly) Power, light-weight, reliability; choose any two.
Always just two!

HP isn't really I said; just math.

There has never been a 125cc two stroke bike that makes 40 ft-lbs of torque (that is why you have to twist their nuts to make them go!). A 125cc 2 stroke GP bike only made 55 hp at like 14K RPM which is only 20.6 ft lbs. I think KTM made the most HP in 125 dirt bikes= 37 HP @ 11K which is only 17ish ft-lbs. But, you are right in that the more rpm you have with a constant torque will always give more HP. That is why when building an engine a flat torque that doesn't fall off in higher rpm is more desirable.
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