The power stroke in a diesel engine is defined as the stroke in which the expansion of hot gases drives the piston down.

The power stroke in a diesel engine is defined as the stroke in which the expansion of hot gases drives the piston down.

• A. Intake stroke
• B. Compression stroke
• C. Power Stroke
• D. Exhaust stroke

Answer: (C)

In a four-stroke engine, the work-producing stage is when the hot, expanding combustion gases push the piston downward, converting chemical energy into mechanical energy that turns the crankshaft. This is the power stroke. After fuel is injected and ignition occurs, the rapid expansion of the hot gases drives the piston down, delivering the engine’s output. The other strokes prepare or eject: the intake stroke brings in air, the compression stroke raises the air’s pressure before ignition, and the exhaust stroke clears spent gases out of the cylinder. In a diesel engine, this power is produced by compression-ignition combustion, where the high compression heats the air and the injected fuel ignites, causing the expansion that drives the piston down during the power stroke.

In a four-stroke engine, the work-producing stage is when the hot, expanding combustion gases push the piston downward, converting chemical energy into mechanical energy that turns the crankshaft. This is the power stroke. After fuel is injected and ignition occurs, the rapid expansion of the hot gases drives the piston down, delivering the engine’s output. The other strokes prepare or eject: the intake stroke brings in air, the compression stroke raises the air’s pressure before ignition, and the exhaust stroke clears spent gases out of the cylinder. In a diesel engine, this power is produced by compression-ignition combustion, where the high compression heats the air and the injected fuel ignites, causing the expansion that drives the piston down during the power stroke.