This calculator isolates the "Power Stroke" phase of the Otto Cycle. It computes values from TDC to BDC at 10 crankshaft degree increments. Select an engine and camshaft intake profile or enter your own values. Then click on the Calculate button.
The results table has the following meanings:
NOTE 1: At BDC the Piston Pressure is zero (0 PSI) with respect to atmospheric pressure (14.7psi), i.e., no NET pressure effect on the piston. This is because the intake valve is open greater than 0.050" lobe lift (see IVC ABDC under Valve Events in camshaft specs). Effectively, compression pressure is all leaking out the intake valve.
NOTE 2: To compare engine-to-engine, the C.R. must must be set to the same value not the default from the Engine (parameters) pull down menu. In the real Otto Cycle the starting Piston Pressure will also be dependent on the inlet tract Volumetric Efficiency due to such considerations as carb CFM, intake manifold type, intake port flow and intake valve cam profile. See "Intake Stroke Calculator" for some of that computation.
NOTE 3: Avg TQ is "anti-torque" in the sense that it is subtracted from the Avg TQ calculated in the "Power Stroke" calculator as a component of the net torque in the Otto Cycle. See "Exhaust Stroke Calculator" and "Friction Calculator" for the other "anti-torque" components.