I'm comparing the torque developed by two different engine concepts. One is a new fandangled concept being built that lends itself to a simple torque equation F x r x sine theta (Force, radial vector of the crank, angle of Force) because it has only one angle of Force being applied to the rotating mass. The other is a conventional reciprocating engine with a "square" configuration (equal bore and stroke dimensions). In the conventional engine the above equation works for the crank pin angle (piston rod to crank) but nothing is making sense when I try to combine it with the piston pin angle (piston rod to piston). I know all the angles for any given piston/crank position. I just need the trick to solve for any one given position... say 90 degrees from TDC. Any mathy engine types available to help me out with this probably elementary problem?