Comparison Of S.I and C.I Engines

PETROL ENGINE :

1. During the suction stroke, air fuel mixture is drawn from carburetor.

2. Carburetor is used to mix the air and fuel in required proportion.

3. Spark plug is required to ignite the fuel air mixture.

4. Compression ratio varies from 6 to 8.

5. It is Operated by Otto Cycle or constant Volume Cycle.

6. The starting is easy due to the lower compression ratio.

7. Running cost is high because of high cost of fuel.

8. For the same power, less space is required.

9. Initial cost is low.

10. Maintenance cost is less because of fewer parts.

11. Thermal Efficiency is low.

12. These are used for high speed applications.

DIESEL ENGINE :

1. During the suction stroke, air is only drawn from the atmosphere.

2. Fuel Injector or atomizer is required to inject the fuel into cylinder

3. Fuel is ignited automatically by high pressure & temperature air.

4. Compression ratio varies from 12 to 18.

5. It is Operated by Diesel Cycle or Constant pressure Cycle.

6. The starting is little difficult due to higher compression.

7. Running cost is less because of lower cost of fuel.

8. For the same power, more space is required.

9. Initial cost is high.

10. Maintenance cost is more because of more number of parts.

11. Thermal Efficiency is considerable more.

12. These are used for low speed operations.

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