Advantages And Disadvantages Of Two-Stroke Engine Over Four-Stroke Engine
A two stroke cycle engine has twice the number of power strokes than the four stroke cycle engine at the same engine speed.
- For the same power developed, a two stroke cycle engine is lighter, less bulky and occupies less floor area.
- The initial cost of a two stroke cycle engine is considerably less than a four stroke cycle engine
- The weight of the two stroke engine is less than four stroke cycle engine because of the lighter flywheel due to more uniform torque on the crankshaft.
- Since there are only two strokes in a cycle, the work required to overcome the friction and the exhaust strokes is saved.
- It has no valves, so complicated valve actuating mechanism not required.
- It has few moving parts, so compact and simple construction.
- No oil sump for lubrication. Petroil is used for lubrication so it can be used in all positions.
- Low maintenance cost.
- The work required to come over the friction of suction and exhaust is saved.
- As there is a power stroke in every revolution, the turning moment is uniform. Light flywheels are required.
- Incomplete combustion, carbon deposit on the piston head and exhaust port.
- Unstable idling.
- Scavenging problems.
- Less efficient in terms of fuel economy due to part of the unburned charge is rejected during transfer phase.
- More wear and fragile than the four-stroke engine. Shorter life span.
- They are liable to cause high consumption of lubricating oil.
- Worst hydrocarbon emission rate. High polluting.
- High vibration and noisy operation.
- Less thermal and volumetric efficiency.
- Narrow power band compared to a four-stroke engine.
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