This calculator estimates the horsepower and torque performance of a variety of Pontiac engines. It does this by calculating the relevent parameters at each point in the "Otto Cycle".
The calculator estimates the dry air "cylinder fill amount" of the Otto Cycle intake stroke. This is based upon the engine parameters of bore & stroke with consideration given to the cam profile specifications for the intake lobe. This fill amount is then used to estimate the Volumetric Efficiency (VE). The Indicated Mean Effective Pressure (IMEP) during the Otto Cycle power stroke is calculated by instantaneous ignition of the compressed gas pressure produced during the compression stroke of that fill amount. The retarding effect of the pressure drag for the exhaust stroke or Pumping Mean Effective Pressure (PMEP) is estimated based upon the exhaust system and exhaust cam lobe profile specified. The friction losses or Friction Mean Effective Pressure (FMEP) due to piston rings & skirts, bearings and valve train over all cycles are estimated due primarily to stroke and RPM. The net power force or Brake Mean Effective Pressure (BMEP) is calculated from the IMEP less the FMEP & PMEP at RPMs from 2000 to 7000. The torque (TQ) and horsepower (HP)are then calculated from BMEP for those RPMs.
This is not a computer simulation of the Otto Cycle. Rather, it is a programmatic calculator based upon commonly known Pontiac engine parameters and engineering relationships known about the Otto Cycle. "YMMV" (Your Mileage May Vary)