How many full rotations of the crankshaft are required for a complete four-stroke cycle?

In a four-stroke engine, the complete cycle consists of four distinct strokes: intake, compression, power, and exhaust. Each of these strokes corresponds to a specific phase in the operation of the engine.

To understand how many full rotations of the crankshaft are necessary for one complete cycle, it is important to consider the mechanics of engine operation. During the intake stroke, the crankshaft makes a half rotation to draw in the air-fuel mixture. The next half rotation powers the compression stroke where the mixture is compressed. Once the piston reaches the top of the compression stroke, the ignition occurs, producing the power stroke during the next half rotation, which also expels gases. Finally, during the exhaust stroke, the crankshaft completes the final half rotation to push out the exhaust gases.

Therefore, combining these strokes, you have:

• Intake: 1/2 rotation

• Compression: 1/2 rotation

• Power: 1/2 rotation

• Exhaust: 1/2 rotation

This totals four half rotations, which translates to two full rotations of the crankshaft for a complete four-stroke cycle. Hence, the correct answer is two full rotations.