The working cycle of two stroke engine is completed in _______ revolutions of crank shaft.

Explanation

Concept: Two-stroke engines: In this engine, one power stroke is obtained in each revolution of the crankshaft Four-stroke engines: In this type of engine, one power stroke is obtained in two revolutions of the crankshaft Four Stroke Engine Two Stroke Engine Four operations (suction, compression, power, and exhaust) take place in the four strokes of the piston The four operations take place in two strokes of the piston It gives one power stroke in the four strokes, i.e. in two revolutions of the crankshaft. As such three strokes are idle strokes The power stroke takes place in every two strokes i.e. one power stroke for one revolution of the crankshaft Due to more idle strokes and non- uniform load on the crankshaft, a heavier flywheel is required The engine has a more uniform load as every time the piston comes down it is the power stroke. As such a lighter flywheel is used The engine has more parts such as valves and its operating mechanism. Therefore, the engine is heavier The engine has no valves and valve operating mechanism; Therefore, it is lighter in weight. The engine is costlier as it has more parts The engine is less expensive as it has a lesser number of parts The engine efficiency is more as the charge gets completely burnt out. Consequently, fuel efficiency is more The efficiency is less. A portion of the charge escapes through the exhaust port, and because of this, the fuel efficiency is less. Important Points Advantages of the stroke engine over four-stroke engine are Low cost More uniform torque and hence lighter flywheel is needed Because of one power stroke for one revolution, power produced for same size of engine is more Lightweight and simplicity due to the absence of the valve mechanism.