Why more lubricating oil is needed in two-stroke engines than four stroke engines?
Answers
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FOUR STROKE ENGINE
Four-stroke engines are lubricated by oil held in an oil sump. The oil is distributed through the engine by splash lubrication or a pressurized lubrication pump system; these systems may be used alone or together.
Splash lubrication is achieved by partly submerging the crankshaft in the oil sump. The momentum of the rotating crankshaft splashes oil to other engine components such as the cam lobes, wrist pins and cylinder walls.
Pressurized lubrication uses an oil pump to provide a pressurized film of lubricant between moving parts such as the main bearings, rod bearings and cam bearings. It also pumps oil to the engine’s valve guides and rocker arms.
TWO STROKE ENGINE
Two-stroke engines collect some oil beneath the crankshaft; however, two-stroke engines employ a total-loss lubrication system that combines oil and fuel to provide both energy and engine lubrication. The oil and fuel are combined in the cylinder’s intake tract and lubricate critical components such as the crankshaft, connecting rods and cylinder walls.
Oil-injected two-stroke engines inject the oil directly into the engine, where it mixes with the fuel, while premix two-stroke engines require a fuel-oil mixture that is combined before being installed in the fuel tank. In general, two-stroke engines are known to wear more quickly than four-stroke engines because they don’t have a dedicated lubricant source.