Distinguish, differentiate, compare and explain what is the difference between two stroke and four stroke engine.
Difference between two stroke and Four stroke engine
- Two stroke engine have no valves but only ports. The four-stroke engine consists of valves and valve mechanism.
- Two-stroke has lower volumetric efficiency because of lesser time for induction. Volumetric efficiency of four-stroke engine is more due to greater time of induction.
- Due to light weight, simplicity and absence of valve mechanism, initial cost is less in two stroke engine while due to heavy weight and complication of valve mechanism, initial cost is high in four stroke engine.
- In first, the cycle is completed in two stokes of the piston or in one revolution of the crank shaft. In second, the cycle is completed in four strokes of the piston or in two revolutions of the crank shaft.
- In two stroke, more uniform turning movement and hence lighter flywheel s needed. In four stroke the turning movement is not uniform and hence heavier flywheel is needed.
- For the same power the two-stoke engine is light and compact. For the same power the four-stroke engine is heavy and bulky.
- Because of one power stroke in one revolution greater cooling and lubrication requirement and so greater rate of wear and tear in two stroke. Because of one power stroke in two revolutions lesser cooling and lubrication requirements and so lesser rate of wear and tear in four stroke.
- Lower thermal efficiency and part load efficiency is lesser than four stroke engine.