Advantages And Disadvantages Of Two-Stroke Engine Over Four-Stroke Engine

advantage_and_disadvantage_of_two_stroke_engine

Advantages
  1. Simple mechanism.
  2. Easy to start.
  3. It gives one power stroke per revolution of the crankshaft. High power to weight ratio and significant power boost.
  4. It has no valves, so complicated valve actuating mechanism not required.
  5. It is light weight, 30% lighter than the 4-stroke engine.
  6. It has few moving parts, so compact and simple construction.
  7. No oil sump for lubrication. Petroil is used for lubrication so it can be used in all positions.
  8. Low maintenance cost.
  9. The work required to come over the friction of suction and exhaust is saved.
  10. As there is a power stroke in every revolution, the turning moment is uniform. Light flywheels are required.
Disadvantages
  1. Incomplete combustion, carbon deposit on the piston head and exhaust port.
  2. Unstable idling.
  3. Scavenging problems.
  4. Less efficient in terms of fuel economy due to part of the unburned charge is rejected during transfer phase.
  5. More wear and fragile than the four-stroke engine. Shorter life span.
  6. They are liable to cause high consumption of lubricating oil.
  7. Worst hydrocarbon emission rate. High polluting.
  8. High vibration and noisy operation.
  9. Less thermal and volumetric efficiency.
  10. Narrow power band compared to a four-stroke engine.
Read: 
- Comparison between SI engine and CI engine
- Difference between two-stroke and four-stroke engine

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