In a four-stroke diesel engine, how often does each piston fire?

In a four-stroke diesel engine, each piston fires once every two revolutions of the crankshaft. This is due to the design of the four-stroke cycle, which consists of four distinct strokes: intake, compression, power, and exhaust.

During the first revolution of the crankshaft, the engine completes the intake and compression strokes. The piston moves down to allow air and fuel to enter the combustion chamber during the intake stroke, and then it moves back up to compress this mixture during the compression stroke. It is during the second revolution, specifically after the compression stroke, that the piston fires, creating the power stroke, followed by the exhaust stroke where exhaust gases are expelled.

This cycle ensures that each piston only produces power once every two revolutions of the crankshaft, allowing for a more efficient operation of the engine and subsequently better fuel economy and performance compared to two-stroke engines, which fire every revolution.