Diesel Engines:

A diesel engine is same to the gasoline engine used in most cars. Together engines are internal combustion engines which meaning they burn the fuel-air mixture inside the cylinders. Reciprocating engines are both, being driven through pistons moving laterally in two directions. The mainly of their parts are same. Although a diesel engine and gasoline engine operate along with same parts, a diesel engine, while compared to a gasoline engine of equal horsepower, is heavier because of stronger, heavier materials used to withstand the greater dynamic forces from the higher combustion pressures present within the diesel engine.

The greater combustion pressure is the output of the higher compression ratio used through diesel engines. The compression ratio is a measure of how much the engine compresses the gasses within the engine's cylinder. Inside a gasoline engine the compression ratio (that controls the compression temperature) is limited through the air-fuel mixture entering the cylinders. A lower ignition temperature of gasoline will cause it to burn (ignite) at a compression ratio of less than 10:1. An average car has a 7:1 compression ratio. Within a diesel engine, compression ratios ranging from 14:1 to as high as 24:1 are generally used. The higher compression ratios are possible since only air is compressed, and then the fuel is injected. That is one of the factors which permit the diesel engine to be so efficient. Compression ratio will be elaborates in greater detail later in this module.