The compression ratio of diesel engine is

The compression ratio of diesel engine is ______

Options:

a. less than that of gasoline engine
b. similar to that of gasoline engine
c. more than that of gasoline engine
d. none of the above

Correct Answer: c. more than that of gasoline engine

Explanation:

Compression ratio of an internal combustion engine is represented by the ratio of volume of internal combustion engine at its highest capacity to its lowest capacity of accumulating the air-fuel mixture content. In the piston cylinder engine, it is the ratio of volume of the combustion chamber when piston is at its bottom dead centre to its top dead centre while engine is in operating condition.

In gasoline engine the fuel is premixed with air and then sent to the combustion chamber for compression. Whereas in diesel engine only air is compressed in the combustion chamber and then fuel is injected in the cylinder. As only air is compressed during expansion stroke, it allows piston to compress more volume in the combustion chamber. While in petrol engine, piston has to compress fuel particle also along with the air.

Therefore, the gasoline engine or spark ignition engine cannot compress volume as compared to the diesel engine or compression ignition engine. Therefore, the compression ratio of diesel engine is more than that of gasoline engine.