GENERALLY and for a conventional 2 valve wedge design.

All else being equal( displacement, head flow, compression, cam timing, bobweight, etc) : For the same cubes the longer stroke will produce higher average torque but the peak will occur at a lower RPM. Bigger bore will be lower torque below the long strokes peak and nearly equal achieved at a higher RPM and (again GENERALLY) will achieve slightly higher peak (but not necessarily higher average) horsepower.

When you take "all else being equal" out of the equation you can get excellent results from either combination by selecting parts to 'overcome' the torque or HP "weakness" and some people are very good at this, so the becomes "muddy" whenever exceptions are taken

For Most hemis and canted valve motors and 4 valve motors the bore/stroke difference will generally be more extreme in terms of torque and less extreme in HP. These type cylinder heads are less dependent on adequate valve to bore clearance and, in actuality, even bore diameter for good flow and torque/power production, most production motors are undersquare (smaller bore than stroke) in an attempt to maximize part throttle torque but still achieve excellent top end power.

A little discussed constant of torque in a 4 cycle engine, beyond peak torque (where the highest VE% is achieved) the rotating and reciprocating assembly (ring and bearing friction) begins to act as a brake on the torque output, HP goes up with RPM but the rate of rise (in rpm/sec) begins and continues to slow. This is why (particularly) on the street broad flat torque curves tend to "feel" faster than peaky high RPM "horsepower" motors. Race motors are typically designed and tuned to never have to operate below peak torque so that's quite a different animal.

Last edited by Streetwize; 12/08/11 06:25 PM.

WIZE

World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker!

https://www.youtube.com/watch?v=-mWzLma3YGI

In Car:

https://www.youtube.com/watch?v=PjXcf95e6v0