What is the difference between two-stroke and four-stroke engines?

• A. Two-stroke engines have more cylinders
• B. Four-stroke engines produce more power per cycle
• C. Two-stroke engines complete a cycle in fewer strokes
• D. Four-stroke engines are lighter than two-stroke engines

Answer: (C)

The distinction between two-stroke and four-stroke engines primarily revolves around the number of strokes needed to complete a power cycle. In a two-stroke engine, the entire cycle of intake, compression, power, and exhaust occurs within just two strokes of the piston, which means that the engine can produce a power stroke every revolution of the crankshaft. This results in a design that is generally simpler and can be more compact.

In contrast, a four-stroke engine requires four distinct strokes of the piston to complete one power cycle: the intake stroke, compression stroke, power stroke, and exhaust stroke, which means that it produces one power stroke for every two revolutions of the crankshaft. As a result, this design is inherently more complex and often larger.

This difference in the number of strokes directly affects performance characteristics such as power output and efficiency. Two-stroke engines are known for their ability to produce more power relative to their size compared to four-stroke engines, which have more components involved in their operation. Understanding this fundamental difference helps in grasping the operational principles of each engine type.