Compare/Difference Between Two Stroke and Four Stroke Engine, Neat Sketch

 A comparison of two stoke and four-stroke engines on various aspects are given below: -

S. No	Aspect	Two Stroke Engine	Four Stroke Engine
(i)           (ii)                         (iii)            (iv)                     (v)                     (vi)               (vii)          (viii)              (ix)                    (x)	Completion of cycle/working      Flywheel required          Power produced Weight  Cooling requirement       Cooling requirement        Valve and valve mechanism  Wear and tear  Scavenging          Initial Cost      Efficiency	The thermodynamic cycle is completed in two strokes of the piston or in one revolution of the crankshaft.  One power stroke is available in each revolution of the crankshaft. Thus, turning the moment is more uniform, and a lighter flywheel is required.  More.   Since the power produced is more from the same size of the engine, therefore the engine is lighter and compact.  Greater cooling and lubrication are required because there is one power stroke in each revolution. There are no valves only ports are there.  There are no valves only ports are there.  Higher.  Scavenging (the process of clearing the cylinder after expansion stroke) is required, because there is no exhaust stroke at the end of the expansion stroke.  Because of lightweight and simplicity due to the absence of valve mechanism, initial cost of the engine is less.  The volumetric and thermal efficiencies are high. Part load efficiency is better compared to a two-stroke cycle engine.	The cycle is completed in four strokes of the piston or in two revolutions of the crankshaft.  One power stroke is available in every two revolutions of the crankshaft. Thus, the turning moment is not so uniform and a heavier flywheel is required.  Less.    Since power produced is less from the same size of the engine, therefore the engine is heavier and bulkier.  Lesser cooling and lubrication are required because there is only one power stroke in two revolutions. It contains valve and valve mechanisms.  It contains valve and valve mechanism.  Lower.  No need of scavenging because there is an exhaust stroke at the end of the expansion stroke.      Because of the heavyweight and complicated valve mechanism, the initial cost of the engine is more.  The volumetric and thermal efficiencies are low. Part load efficiency is poor than four-stroke cycle engine.