Compression ratio

Compression ratio refers to the ratio of the total volume of the cylinder to the volume of the combustion chamber, which indicates the degree to which the gas in the cylinder is compressed when the piston is moved from bottom dead center to top dead center. Compression ratio is an important parameter to measure the performance index of automotive engines. In general, the greater the compression ratio of the engine, the higher the pressure and temperature of the mixture gas at the end of the compression stroke, and the faster the combustion rate, the greater the power of the engine and the better the economy. However, when the compression ratio is too large, not only can it not further improve the combustion condition, but it will cause abnormal combustion phenomena such as detonation and surface ignition, which in turn will affect the performance of the engine. In addition, the increase in engine compression ratio is also limited by exhaust pollution regulations.