1. Number of Strokes per Cycle:
* Two-stroke: Completes a power cycle in two strokes of the piston (intake and power)
* Four-stroke: Completes a power cycle in four strokes of the piston (intake, compression, power, exhaust)
2. Intake and Exhaust Process:
* Two-stroke: Intake and exhaust occur simultaneously through ports in the cylinder wall, controlled by piston movement.
* Four-stroke: Intake and exhaust occur separately, controlled by valves.
3. Lubrication System:
* Two-stroke: Lubrication is typically achieved by mixing oil with fuel.
* Four-stroke: Lubrication is handled by a separate oil sump and pump, keeping oil separate from fuel.
4. Power Output:
* Two-stroke: Generally produces more power per unit volume than a four-stroke engine due to the shorter cycle.
* Four-stroke: Typically offers better fuel efficiency and lower emissions than a two-stroke engine.
5. Maintenance:
* Two-stroke: Requires more frequent maintenance, including oil changes and cleaning of combustion chambers.
* Four-stroke: Requires less frequent maintenance compared to two-stroke engines.
6. Applications:
* Two-stroke: Used in applications where power-to-weight ratio is important, such as motorcycles, chain saws, and outboard motors.
* Four-stroke: Found in most automotive vehicles, generators, and industrial applications.
7. Emissions:
* Two-stroke: Tend to produce higher emissions due to unburnt fuel and oil exiting the engine.
* Four-stroke: Produce lower emissions due to a more complete combustion process.
8. Noise:
* Two-stroke: Can be noisier than four-stroke engines due to the inherent design.
* Four-stroke: Generally quieter than two-stroke engines.
9. Complexity:
* Two-stroke: Simpler design with fewer moving parts.
* Four-stroke: More complex design with valves, camshafts, and other components.
10. Cost:
* Two-stroke: Typically less expensive to manufacture.
* Four-stroke: Usually more expensive to produce.
In summary: Two-stroke engines offer a simpler design, higher power output, and a lower initial cost, but come with drawbacks like higher emissions, lower fuel efficiency, and increased maintenance. Four-stroke engines, on the other hand, provide better fuel efficiency, lower emissions, and less frequent maintenance, but are more complex and costly to manufacture.
