This calculator isolates the "Exhaust Stroke" phase of the Otto Cycle. It computes values from BDC to TDC at 10 crankshaft degrees increments. Select an engine and camshaft exhaust profile or enter your own values. Then click on the Calculate button.
The results table has the following meanings:
NOTE 1: At BDC, Piston Pressure starts at an nominal 0.275 times compression ratio (Engine parameters C.R.) less atmospheric pressure 1.0Bar(14.7psi). This is about 1.1Bar(16PSI) to 2.0Bar(29PSI) for compression ratios 7.6:1 to 10.75:1 respectively. The choice of exhaust system (pulldown menu) determines the actual multiplier.
NOTE 2: Between BDC and TDC the Piston Pressure varies by cylinder swept volume (maximum at BDC and minimum at TDC). At TDC, the net Piston Pressure is zero.
NOTE 3: 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. Likewise for Exhaust System
NOTE 4: 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 "Compression Stroke Calculator" and "Friction Calculator" for the other "anti-torque" components.