I often wonder how horse power and torque is messured? Anyone know?

 

Torque is measured in lb-ft, or pound-feet (I don't think it matters if it's lb-ft or ft-lbs). This unit is a measurement of how much force acting on a lever arm, or any object, causes it to rotate, sort of a "circular force." Horsepower is related to Torque like so:
(Torque x rpm)/5250 = Horsepower.

 

what does the 5250 relate to?

 

It's magic.

No seriously, it's actually 5252 and here's something I stole from somewhere else:

Applying 1 lb of force 1 ft from the fulcrum for a complete revolution will lead to;

W = F*2*pi*r = 1 lb * 2*pi * 1 ft = 2*pi lb-ft = 6.283 lb-ft

If it takes one minute to complete this revolution, then the power is;

P = W / time = 6.283 lb-ft / min

1 hp is defined as 550 lb-ft / s = 33,000 lb-ft / min

Therefore, applying 1 lb-ft of torque in one minute (1 rpm) = [6.283 lb-ft / min] / [33,000 lb-ft / min] = 1 / 5252 of 1 hp.

From this you can then calculate the number of hp from any given torque and rpm:

hp = torque (lb-ft) * rpm / 5252

 

Man, that would have been awsome if you knew that off the top of your head! But anyways, thanks, Im going to save it on my H-T note pad and someday sort it all out. To late right now to even try. Thanks again.

 

more food for thought: http://www.howstuffworks.com/horsepower.htm

 

The horsepower vs. torque debate is actually quite simple.

History lesson: Back in the day, James Watt reached the epiphany that basic torque measurements of his nascent steam engine did not accurately portray its work potential as RPM fluctuated. Consequently, Watt invented the rate of torque delivery as HP.

What's all that mean? Keyword: rate, measuring anything (pay, velocity, torque) in increments of time. Just like pay and velocity rely as hours ("X" dollar/hour; "X" MPH) as incremental units, Watt decided to measure the rate of torque production in minutes. Consequently, Watt declared a total of 33,000 ft. lbs of total torque produced in one minute as one horsepower. Dividing that figure by 6.28 (2 x pi) yields 5252 - the constant from which HP is calculated as a function of torque.

This formula should make more sense now:HP = RPM X TQ/5252

Now apply Watt's dilemma to the internal combustion engine. For the sake of simplification, image a motor with a completely flat torque curve with an operation range between 1000 and 7000 RPM generating 100 lbs/ft of torque. Anywhere between those two figures, torque output is identical. However, torque is an instantaneous reading that does not even acknowledge the existence of time.

As time elapses, and RPM increase, instantaneous torque production does not change whatsover, but total torque produced proliferates dramatically. Per the HP formula, at 1K RPM, the above motor generates 100 lbs/ft of torque and 19 HP. Now, at 7K RPM, the motor still produces the same 100 lbs/ft of torque, but 133 HP. The instaneous rotational force/torque the motor produced did not change at all, but thanks to multiplication via RPM, the total torque output at 7000 RPM in one minute of time yields far greater power.

Recite this mantra 10 times: HP is nothing more than total torque produced in one minute of time. Keep the debate simple Watt must be rolling over in his grave.