Quote:
Originally posted by scargo70
So it seems that torque is a more a function of momentum of the piston that is speed(ie hig revs).
|
Let's expand on the formula in the previous post to clarify the relationship between HP and torque.
The physic-guru James Watt found that a typical horse could lift a 550 lb weight one foot in one second. This translates to 33,000lbs in one minute. That's our modern measure of a horsepower. However, you notice that it would be measured in pounds moved over one foot? Pounds-foot? That sounds like torque! You're right! You can't measure horsepower. A dyno measures torque and we use some math to show HP.
Suppose we have a circle that is one foot in diameter. We extert one pound of resistance against it. That means in one full revolution we have moved one pound through the circumference (which is 2*Pi) or (3.14159*2) = 6.2832 feet.
Now, we know that one hp is 33,000 foot-pounds, right? Take the 33,000 and divide it by the 6.2832 feet of one revolution, and we have the 5252 number. That's where the relationship comes from. Blame Watt for the formula!
We end up with: HP = torque * (RPM / 5252)
It's simple, but the design and creation of en engine's torque curve is not. Lots of variables.