Start of injection, often referred to as injection timing, is the exact moment at which fuel injection into the combustion chamber begins. The typical method of expressing it is in terms of crank angle degrees (CAD) in relation to the compression stroke's top dead center (TDC). The diesel engine has long been the preferred choice for power plants, transportation, engineering equipment, and agricultural gear, in addition to the military. This is because of the diesel engine's excellent heat efficiency, robust reliability, sufficient and consistent power, and other qualities.