Constant-Volume Cycle

A four-stroke cycle used in gasoline and natural gas engines in which, ideally, combustion takes place at constant volume. Combustion is so rapid that no piston movement occurs during combustion and the maximum pressure attained in the cylinder greatly exceeds the compression pressure. No engine achieves true constant volume combustion in practice, but small, high-speed, diesel engines tend toward this cycle.

Also known as Otto Cycle.