Piston Inline Compression-ignition Engine

In a diesel engine, named after its inventor, Rudolf Diesel, as the piston moves down, air is drawn into the cylinder, and the air is compressed as the piston moves up, but it is compressed to about one-twentieth of its original volume, which raises its temperature to about 1000°F.   As the piston reaches the top of its travel, the fuel is injected into the cylinder to mix with the air, which is hot enough to ignite spontaneously.   Therefore, there is no spark ignition required.   Speed is controlled by the amount of fuel injected. ^{How 705}   Many diesel engines use two-stroke piston cycle rather than four-stroke, gasoline ("Otto") engines.   Diesel engines are the dominant engines in heavy-duty trucks and tractors, construction vehicles, buses, and marine vessels.

Four stroke diesel engine

Two stroke diesel engine

Glow plugs are used only to warm the combustion chamber the the engine is cold.

Combustion chambers are of 3 types: ^{Erjavec 199-200}

1. Open combustion chamber is located directly inside the piston.   Diesel fuel is injected directly into the center of the chamber.   The shape of the chamber and the quench area produces turbulence.

2. Precombustion chamber is a small, second chamber connected to the main chamber.   On the power stroke fuel is injected in the small chamber where combustion starts.   It then spreads to the rest of the chamber.   This design allows lower fuel injection pressures and simpler injection system.

3. Turbulence combustion chamber

Comparison of diesel and gasoline engines: