Why do we not use the same technology to start both Si CI engines?

Why don’t we use the same technology to start both SI and CI?

So in case of SI engine, the compression ratio is not sufficient for fuel to burn so a spark plug is used, whereas in ci engine, the compression ratio is so high that due to its internal heat the fuel is combusted so there is no need for a spark plug. So the technology used in SI engine is different from CI engine.

How the ignition process of SI engine is different from CI engine?

in S.I engines,ignition process is carried out with the help of a spark plug which ignites a mixture of air and fuel that is compressed in the combustion chamber. Whereas,a diesel engine also known as Compression Ignition (C.I) engine works on the basis of Diesel cycle or Constant pressure heat addition cycle.

For petrol (SI) engines the main limitation of supercharging is knocking. As we know during supercharging pressure and temperature of air and fuel increases, which reduces ignition delay and results in engine knocking problems. … If the air pressure is to be increased, power input to the supercharger is to be increased.

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Which is more efficient CI or SI?

CI engines have higher Thermodynamic Efficiency

With a higher compression ratio in CI engines as compared to SI engines, CI engines have a higher thermodynamic efficiency since more work is done with each expansion stroke.

Which engine gives more power?

Effective RPM: Petrol engines provide power on more of the RPM band while diesel engines provide most of their power on the lower range of the RPM band. Fuel Efficiency: Due to the higher RPM band, petrol engines are less fuel efficient than their diesel engine counterparts.

Why CI engine is heavier than SI engine?

Weight of the engines: In CI engines the compression ratio is higher, which produces high pressures inside the engine. Hence CI engines are heavier than SI engines. … In the case of SI engines the lower compression ratio reduces their potential to achieve higher thermal efficiency.

How does CI engine works?

Diesel vehicles are similar to gasoline vehicles because they both use internal combustion engines. … In a compression-ignited system, the diesel fuel is injected into the combustion chamber of the engine and ignited by the high temperatures achieved when the gas is compressed by the engine piston.

What is the full form of SI and CI engine?

Spark-Ignition (SI) engine, is a type of internal combustion engine in which the air-fuel mixture inside the combustion chamber of the engine is ignited by a spark from a spark plug. Generally, the petrol engine is a Spark Ignition (SI) engine, whereas the diesel engine is a Compression Ignition (CI) engine.

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What is supercharging suitability for SI and CI engines?

Supercharging in CI engine:

Volumetric and thermal efficiency decreases due to increase in intake pressure and temperature but increase in density due to pressure compensates for this. One more advantage due to supercharging the improvement in combustion allows poor quality of fuel can be used in diesel engine.

What are the supercharging limits of Si engine?

Supercharging Limits of SI engines:- The degree of supercharging in SI engines is chiefly limited by the knock. This increase in pressure and usually in temperature also, because of supercharging reduces ignition delay and consequently the engine has a knocking tendency at these pressure.

What is supercharging in SI engine?

When a pressure higher than atmospheric is used a greater mass of air enters the cylinder and the engine is supercharged. This is achieved by the use of some kind of air pump to deliver air to the engine and such a device is called a supercharger.

How does a CI engine start?

In a petrol engine, the fuel/air mixture is ignited by a spark . In a diesel engine, ignition is achieved by compression of air alone. … The heat from compression fires the fuel/air mixture immediately, causing it to burn and expand. This forces the piston downwards, turning the crankshaft .

What are the 3 main engine systems?

Main Engine Systems

  • Lubricating Oil System. …
  • Main Bearing Oil System. …
  • Crosshead Bearing Oil System. …
  • Cylinder Lubrication System. …
  • Cooling Water System. …
  • Cooling Water System Description. …
  • Fuel Oil System. …
  • Circulation System.


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Which must be moved to start the engine?

To make an engine start it must be turned at some speed, so that it sucks fuel and air into the cylinders , and compresses it. The powerful electric starter motor does the turning. Its shaft carries a small pinion ( gear wheel) which engages with a large gear ring around the rim of the engine flywheel .

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