In a four-stroke engine, how many crankshaft revolutions are required for a complete intake, compression, power, and exhaust cycle?

In a four-stroke engine, how many crankshaft revolutions are required for a complete intake, compression, power, and exhaust cycle?

• A. 2
• B. 1
• C. 3
• D. 4

Answer: (A)

The four-stroke cycle is completed over two full turns of the crankshaft. Each stroke spans 180 degrees, so four strokes (intake, compression, power, exhaust) cover 4 × 180 = 720 degrees, which is two revolutions. A single revolution would only finish two strokes, leaving the cycle incomplete, while three or four revolutions would exceed a single cycle.

The four-stroke cycle is completed over two full turns of the crankshaft. Each stroke spans 180 degrees, so four strokes (intake, compression, power, exhaust) cover 4 × 180 = 720 degrees, which is two revolutions. A single revolution would only finish two strokes, leaving the cycle incomplete, while three or four revolutions would exceed a single cycle.