Both 4-stroke and 2-stroke diesel engines have passages cast in the head to carry oil for lubrication and water for cooling.
The combustion chamber can be formed in the cylinder head or the piston crown. These chambers are different from those in gasoline engines. That’s because diesel fuel is different from gasoline and so is the way it is ignited.
In a gasoline engine, fuel already mixed with air enters the cylinder, and a spark plug ignites it. That’s why gasoline engines are called spark-ignition engines.
In a diesel engine, just air enters the combustion chamber first. It is then highly compressed, and its temperature rises. Fuel is injected. It ignites, due to heat of the compressed air. That’s why diesels are called compression-ignition engines.
Injectors are mounted in the cylinder head so that they reach into the combustion chamber.
They inject fuel into the chamber in atomized form - in a fine spray.
Atomized fuel burns more efficiently than liquid fuel.
Different spray patterns are used, depending on the shape of the combustion chamber.
