In a two-stroke diesel engine, how many revolutions does the crank shaft spin during one power stroke?

• A. 2
• B. 1
• C. 0.5
• D. 1.5

Answer: (B)

In a two-stroke engine, the complete cycle from intake through compression, power, and exhaust is designed to occur within a single turn of the crankshaft. The work-producing event, the power stroke, is tied to that single crankshaft revolution, so one full rotation of the crankshaft corresponds to one power stroke. This is what sets two-stroke engines apart from four-stroke engines, where a full cycle spans two crankshaft revolutions and the power stroke occurs over the course of those cycles.