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Important point of Spark ignition (S.I) and Combustion ignition (C.I) engines

Spark ignition and combustion ignition engines important points, simple description and applications with practical examples

Spark ignition (S.I) engine key points

  • Otto cycle is used in S.I engines
  • Petrol is used as fuel
  • Air fuel ratio in these engines is between 10:1 to 20:1
  • Compression ratio maximum value is 11, average value is between 7 to 9, maximum value of the compression ratio is depends on anti-knock of fuel
  • Spark ignition is used for combustion of the air fuel mixture
  • Compression pressure is between 7 bar to 15 bar and maximum pressure is between 45 bar to 60 bar
  • These engines are used for high speed operation and speed range is between 2000 to 6000 r.p.m
  • Power is controlled by governors
  • Calorific value in spark ignition is 44MJ/kg
  • Low maintenance cost is required in S.I engines
  • Running cost is high
  • Supercharging is used only in aircraft engines
  • Spark ignition (S.I) is used in motorcycles, scooters, air crafts, mopeds etc.

applications-of-spark-ignition-engine



Combustion ignition (C.I) engine key points

  • Diesel cycle and dual cycles are used in C.I engines
  • Dual cycle for high speed engines and diesel cycle for low speed engines
  • Diesel is used as fuel
  • Air fuel ratio in these engines is between 18:1 to 100:1
  • Compression ratio value is between 12 to 24, average value is between 15 to 18, maximum value of the compression ratio is depends on stresses
  • Compression ignition is used for combustion of the air fuel mixture
  • Compression pressure is between 30 bar to 50 bar and maximum pressure is between 60 bar to 120 bar
  • These engines are used for high, medium and low speed operation and speed range is between 400 to 3500 r.p.m depends on usage speed
  • Power is controlled by governors
  • Calorific value in spark ignition is 42MJ/kg
  • High maintenance cost is required in C.I engines
  • Running cost is low
  • Tractors, trucks, buses and generators etc.

applications-of-combustion-ignition-engine



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