Original H-O'sOtto CycleExhaust Stroke Calculator

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:

• Piston Pressure is the NET pressure on the piston top at the crankshaft rotation position shown.
• Rod Angle is the angle in degrees between the bore centerline and the line between the small & big rod end centers.
• Side Thrust is the sidewards force on the piston due to Rod Angle.
• Rod Force is the downwards force on the connecting rod due to NET Piston Pressure over the area of the piston top through the Rod Angle. It is coincident with the connecting rod centerline acting on the crank pin journal centerline.
• aEffect Lever is the effective lever arm in inches. Its maxiumum value is half of stroke which occurs at the optimum crank angle.
• Effect Torque is the Rod Force times the Effect Lever.
• Avg TQ is the average Area Under Curve of Effect Torque from BDC to TDC.

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.

 Exhaust System

 Avg TQ:
 CrankAngle |PistonPressure |Rod|Angle |Side|Thrust |Rod|Force |Effect|Lever |Effect|Torque BDC 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 TDC