Which engine design requires two full crankshaft rotations to complete one cycle?

Which engine design requires two full crankshaft rotations to complete one cycle?

• A. Two Stroke
• B. Rotary
• C. Four Stroke
• D. Diesel

Answer: (C)

The main idea is how many crankshaft revolutions a full power cycle needs in common engine designs. In a four-stroke engine, the cycle consists of four strokes: intake, compression, power, and exhaust. Each stroke takes 180 degrees of crankshaft rotation, so four strokes add up to 720 degrees—two full revolutions of the crankshaft. That’s why this design requires two complete crankshaft turns to finish one cycle. Two-stroke engines, by contrast, complete a cycle in one crankshaft revolution because the intake/compression and power/exhaust events overlap differently. The rotary engine uses a rotor rather than a conventional crankshaft, so its cycle timing isn’t measured in crankshaft revolutions the same way. Diesel refers to the ignition method and can be implemented as either four-stroke or two-stroke, but the description of needing two full crankshaft rotations points to the four-stroke design.

The main idea is how many crankshaft revolutions a full power cycle needs in common engine designs. In a four-stroke engine, the cycle consists of four strokes: intake, compression, power, and exhaust. Each stroke takes 180 degrees of crankshaft rotation, so four strokes add up to 720 degrees—two full revolutions of the crankshaft. That’s why this design requires two complete crankshaft turns to finish one cycle.

Two-stroke engines, by contrast, complete a cycle in one crankshaft revolution because the intake/compression and power/exhaust events overlap differently. The rotary engine uses a rotor rather than a conventional crankshaft, so its cycle timing isn’t measured in crankshaft revolutions the same way. Diesel refers to the ignition method and can be implemented as either four-stroke or two-stroke, but the description of needing two full crankshaft rotations points to the four-stroke design.