So... you say your a wrench ?

There is alot more to it than just the stroke. Compression ratio, ignition timing, all play a role in developing torque.

 

Well, the longer the stroke, the longer the duration power is applied to the crank, so the answer would be stroke. All thing being equal.

 

Absolutly true!

 

The cranckshaft "throw" is determined by the length of the stroke. Imagine a bicycle. Have a 200# guy standing on the crank. A 100mm crank is going to put less torque on the drive train than the same guy standing on a bike with a 175mm crank.

 

H.P. is a mathamatical calculation of Torque. To wit: Power is torque multiplied by engine speed to produce a measurement of the engine's ability to do work over a given period of time. Horsepower is a measure of force in pounds against a distance in feet for a time period of one minute. By substituting an arbitrary lever length for the crankshaft stroke, you can calculate the distance traveled around the crank axis in one minute multiplied by rpm and known torque to arrive at the formula for horsepower.
Because torque and rpm are divided by 5252, torque and horsepower are always equal at 5252 rpm. If you solve the equation at 5252 rpm, the rpm value cancels out, leaving horsepower equal to torque. If you plot torque and horsepower curves on a graph, the lines will always cross at 5250 rpm (rounded off). If they don't, the curve is undoubtedly bogus.
Torque is the static measurement of how much work an engine does, while power is a measure of how fast the work is being done. Since horsepower is calculated from torque, what we are all seeking is the greatest-possible torque value over the broadest-possible rpm range. Horsepower will follow suit, and it will fall in the engine speed range dictated by the many factors that affect the torque curve.
Are you still lost?

 

Hey, I,ve been to college.