What is CI engine and SI engine?

Si engine is internal combustion engine that operates on the principle of spark ignition. It uses petrol and utilizes the Otto cycle. The diesel (Ci) engine is also an internal combustion engine, which uses diesel fuel and operates on diesel cycle.

What is difference between SI engine and CI engine?

The Spark Ignition (SI) engine, as its name indicates uses spark to ignite the fuel. … And in Compression Ignition (CI) engine, the air is compressed within the cylinder and the heat of this compression air is used to ignite the fuel.

What is meant by CI engine?

Compression ignition (CI) engines

In a compression ignition engine only air or air plus residual combustion gases from the exhaust known as exhaust gas recirculation (EGR) is inducted into the chamber during the intake stroke, and compressed during the compression stroke.

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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Is diesel engine a SI engine?

Technically petrol engines are called as spark ignition engines ( SI ) and diesel engines are called as compression ignition engines (CI ) . … At the end of compression the spark is ignited and then combustion takes place from where the power stroke is obtained.

Which is better CI or SI engine?

Thermal efficiency: Due to lower compression ratio, maximum value of thermal efficiency is lower in an S.I engine compared to that of C.I. 7… Weight : S.I engines are generally lighter in weight due to their lower peak pressures as compare to C.I engines that are generally heavier, due to higher peak pressure.

What type of fuel is used for SI engine?

The most common alternative fuels for SI engines are ethanol in blends with gasoline as well as compressed natural gas (CNG) , liquefied natural gas (LNG) , and liquefied petroleum gas (LPG) . Biodiesel, synthetic diesel, green diesel, and DME are the most common alternative fuels for CI engines.

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.

Is fuel pump used in CI engine?

CI Engine Fuel Supply System

The high-pressure pump is the main and the most complicated component of the fuel system. … Both coarse filters and fine filters are used for filtration of the fuel oil. The fuel feed pump transfers fuel from the tank to the high-pressure pump (injection pump).

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Why diesel engines are called CI engines?

Diesel engines are sometimes called compression-ignition engines because initiation of combustion relies on air heated by compression rather than on an electric spark. … As the piston moves away from this position, fuel injection is continued, and the combustion process then appears as a nearly constant-pressure process.

What is the full form of SI units?

Système international

3. Which of the following does not relate to spark ignition engine? Explanation: Fuel injector is not related to spark ignition engine as there is no fuel injection in spark ignition engine.

What are the advantages of SI engine?

Advantages Of SI Engine:

  • 1) SI Engines are low in cost.
  • 2) SI Engine produces less pollution as compared to CI Engine.
  • 3) These engines are smaller as compared to CI engine and hence requires less space.
  • 4) These engines are lightweight.
  • 5) The cost of an SI engine is lower as compared to CI Engine.


What are the disadvantages of diesel engines?

Cons of diesel cars

  • Diesel cars tend to be more expensive to buy than similar petrol models.
  • Diesel fuel usually costs more.
  • Servicing can be more expensive, although you don’t need to do it as often.
  • Insurance can be 10-15% higher. [ …
  • Diesel cars produce a lot more NO2.


Why there is no spark plug in CI engine?

For less calorific value we do not get more horse power. But diesel have more heat developed during combustion thus developing more power than petrol engines. Thus there is no need of Sparking the air- fuel mixture in the diesel engine.

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