In diesel engine, the compression ratio in comparison to expansion ratio is

In diesel engine, the compression ratio in comparison to expansion ratio is More. Compression ratio, in an internal-combustion engine, degree to which the fuel mixture is compressed before ignition. It is defined as the maximum volume of the combustion chamber (with the piston farthest out, or bottom dead centre) divided by the volume with the piston in the full-compression position (with the piston nearest the head of the cylinder, or top dead centre).