Controls

Compression ratio

Heat input Q_in

Heat-capacity ratio gamma

Intake temperature

Animation speed

Presets

How it works

Air-standard Otto cycle, 1 kg of air, R = 0.287 kJ/kg K, cv = R/(gamma-1):

1-2 adiabatic compression: T2 = T1 r^(gamma-1)
2-3 heat addition at constant volume: T3 = T2 + Q_in / cv
3-4 adiabatic expansion: T4 = T3 r^(1-gamma)
4-1 heat rejection at constant volume
eta = 1 - r^(1-gamma) = W_net / Q_in
MEP = W_net / (v1 - v2)

Efficiency depends only on compression ratio and gamma; real petrol engines are limited near r ~ 11 by knock.

Thermal efficiency-

Net work-

MEP-

Peak P / T-

Stroke-

Knock risk-

Otto Cycle: 2D Four-Stroke Engine

Ideal air-standard Otto cycle with animated piston, live P-V and T-S diagrams, work and efficiency.