FAA Powerplant Written Practice Test

Which stroke follows the combustion stroke in a 4-stroke cycle?

1. Intake stroke

2. Power stroke

3. Exhaust stroke

4. Compression stroke

The correct answer is: Exhaust stroke

In a 4-stroke engine cycle, the stroke that follows the combustion stroke, also known as the power stroke, is the exhaust stroke. During the power stroke, the fuel-air mixture is ignited, resulting in an expansion of gases that drive the piston down. Once this stroke is complete, the engine needs to expel the spent combustion gases from the cylinder to prepare for the next intake of fresh air and fuel. The exhaust stroke begins after the power stroke; the piston moves back up the cylinder, and the exhaust valves open to allow the burnt gases to exit. This stroke is crucial because it ensures that the cylinder is clear of exhaust gases, enabling efficient operation during the intake stroke that will follow. Properly functioning exhaust and intake strokes are key components in maintaining the overall efficiency and performance of the engine.