Question

During which strokes does the piston move downward in a four-stroke internal combustion engine?


intake and exhaust

power and intake

compression and power

compression and exhaust

Answer 1

In a four-stroke internal combustion engine, the piston's downward movement occurs during the **intake** and **power** strokes.

- **Intake Stroke**: During this stroke, the piston moves down, creating a vacuum that draws in the air-fuel mixture (or just air, in the case of diesel engines) into the cylinder.
- **Power Stroke**: After combustion, the pressure from the expanding gases pushes the piston downward, generating power.

Therefore, the correct answer is **power and intake**.