Criteria S.I. Engine (Petrol or Spark Ignition Engine) C.I. Engine (Diesel or Compression Ignition Engine) Working Cycle Works on Otto Cycle or Constant Volume Cycle. Works on Diesel Cycle. Mixture During Suction Stroke Takes a mixture of air and petrol during the suction stroke. Takes only air during the suction stroke. Fuel Used Uses petrol as fuel. Uses diesel as fuel. Compression Ratio Has a compression ratio that varies from 6 to 10. Has a compression ratio that varies from 16 to 20. Engine Weight and Cost S.I. engines are lighter and cheaper. C.I. engines are heavier and costlier. Initial Cost Initial cost is lower compared to C.I. engines. Initial cost is high due to high compression ratio. Starting Starting is easy. Starting is difficult, especially in cold conditions. ...
Working Principle of 2-Stroke and 4-Stroke Cycle Engines
•Four-Stroke Engine :- The engine that requires four strokes of the piston or two revolutions of the crankshaft to complete the working cycle.
•Strokes:-
1. Suction Stroke:- In this stroke, the fuel is supplied to the cylinder.
2. Compression Stroke:- In this stroke, the fuel is compressed in the cylinder.
3. Expansion or Power Stroke:- In this stroke, the fuel is burnt to produce power.
4. Exhaust Stroke:- In this stroke, the burnt gases are exhausted to make space for fresh fuel.
•Two-Stroke Cycle Engine:-The engine that requires two strokes of the piston or one revolution of the crankshaft to complete the working cycle.