Comparison of Spark Ignition (SI) and Compressed Ignition (CI) engines
|
|
Spark Ignition (SI) engine |
Compressed Ignition (CI) engine |
|
Working cycle |
Heat is added at constant volume. It works on Otto cycle. | It works on diesel cycle. Heat is added at constant pressure. |
|
Compression ratio |
6 to 10 (low compression ratio) | 16 to 20 (high compression ratio) |
|
Ignition of fuel |
Spark plug is used | Air is compressed so ignition occurs due to high temperature of air. |
|
Introduction of fuel |
Carburetor is used. Multi point fuel injection system is also used now a day. | Fuel pump and injector are used. |
|
Type of fuel |
Petrol or gasoline | Diesel |
|
Thermal efficiency |
Lower | Higher |
|
Load control |
Fuel-air mixture is controlled by throttle | Only the quantity of air is controlled. |