How Diesel Engines Work

The main distinction between a diesel engine and a gasoline engine lies in the type of ignition. Gasoline engines operate on a spark driven ignition, where diesel engines employ a compression type ignition for igniting the fuel. In diesel engines, air is drawn into the engine and undergoes high compression that heats it rapidly. As a result of this high temperature, the diesel fuel which is drawn into the engine will ignite.

In diesel engines, air and fuel are combined within the engine at different stages, where with gasoline engines, air and gasoline mix at the same point to cause combustion. Another difference lies in the fuel injection methods of each engine. Diesel engines rely on a fuel injector to bring fuel into the engine, where gasoline engines use a carburetor. In gasoline engines, fuel and air are sent to the engine together and then compressed by the engines pistons and are then ignited by spark plugs. This air and fuel mixture limits compression ratios and overall efficiency of the engine. A diesel engine compresses only air, increasing the compression ratio to a much higher point from 14:1 and up to 25:1, where the compression ratio of a gasoline engine is only 8:1 up to 12:1.

Diesel engines can be found in two-cycle or four-cycle and are chosen based on the mode of operation. This is based on the choice between air-cooled and liquid-cooled engines. Ideally, a liquid cooled engine would be the wiser choice as the run more quietly during operation and have a more controlled temperature range.

The Advantages of Diesel Engines

A diesel engine is much more efficient when compared to a gasoline engine based on the following points:

Modern diesel engines are quiet and require less maintenance than gasoline engine of comparable size
Diesel engines are more rugged and reliable than gasoline engines
The lack of spark plugs and wires in a diesel engine helps reduce maintenance costs as the fuel in a diesel engine auto-ignites
Gas units tend to burn hotter than a diesel unit does, and therefore have shorter lives when compared to diesel units