What are the differences between a SPARK IGNITION ENGINE and a COMPRESSION INGITION ENGINE?

Question

Does fuel volatility make these types of engine different?

differences besides SI engines using spark plug and CI engines using high pressure.

Answer 1

0. Going as per the naming, it is clear that in SI engines, igniton to the properly mixed air-fuel mixture is provided by an electrical spark and hence they are called so. Whereas in CI engines high temperature caused by compressing the air is sufficient for ignition.Hence they are called CI engines.

1.The CI engine works on Diesel cycle whereas the SI engine works on Otto cycle.

2. The fuel used in CI engine is Diesel that has less self-ignition tendency and is less volatile. While the fuel used in SI engine is Petrol that burns if left in air at a little bit temperature. It is very volatile.
Let me tell you that in SI engines, aromatics are most preferred fuels whereas in CI engines alkanes are preferred as fuels.
A fuel must pass through four criteria before it is used : (a) volatility, (b) anti-knock quality, (c) gum deposits, and (d) sulphur content. Except volatility, other three can be managed.
More volatility means less ignition temperature, which in turn implies that a lower compression ratio can be obtained(as is the case with SI engines). In CI engines, diesel is used that is less volatile than petrol. So an appreciably larger compression ratio can be obtained that yields more efficiency. So volatility of fuels does play a crucial role in determining the efficiency of the Internal Combustion engines.

3. The air-fuel mixture is homogeneous throughout in SI while in CI only air enters and in the cylinder mixture is heterogeneous.

4. In SI engine, properly mixed air-fuel mixture in carburettor enters the cylinder. But in CI engine, only air enters the cylinder.

5. In SI engine, the combustion chamber is smaller because there is no smoke. But in CI engine, due to smoke, combustion chamber has to be larger.

6. In SI engines, knocking is due to pre-ignition. It can result in detonation and can damage the engine altogether. But in CI engines, knocking is due to ignition delay, and hence it is least harmful.

7. The compression ratio is in the range of 6-10 in SI engines whereas in CI engines, it is about 12-20. Hence CI engines are considered efficient than the SI engines.

Answer 2

A spark enginge relies on the spark plug firing to ignite the fuel-air mixture in the cylinder.

In a compression fired engine, the fuel-air mixture is ignited by the heat of compression of the mixture. As the piston moves into the cylinder, reducing the volume, it is compressing the fuel-air mixture. As any vapor is compressed, it is heated. In the case of a compression fired engine, it is heated to the point where the mixture will ignite without the aid of a spark. This is also known as the flash point.

Answer 3

It's the the same difference as a gasoline engine compared to a diesel engine.
The fuel/air mixture in the gas engine is ignited by an electric spark. The fuel/air mixture in a diesel engine is ignited by being compressed very much. The very high compression in a diesel engine causes the fuel/air mixture to get very hot - hot enough that it ignites itself without the need for a spark.

Hope this helps.

Answer 4

a spark plug.

The flash point of the fuel is an important distinction. In a spark engine the fuel is sent into the cylinder with the air and a burnable mixture is compressed. If the flash temperature is reached before the spark time, the engine knocks. (predetonates)

A Diesel engine, (compression) injects the fuel into the top of the cylinder already hot from compression.

Answer 5

in spark ignition engine the the spark plug ignites the air fuel mixture,while in a compression ignition engine the spark is produced when a fine spray of fuel is injecten into the chamber filled with compressed air.

Answer 6

2 considerable products: a million. style of gasoline 2. Spark plugs Diesel gasoline while interior the surprising blend generates adequate warmth on the compression stroke to self ignite. gasoline won't and there fore desires an ignition equipment. while in comparison with a gasoline engine, the diesel engine has a extra robust compression ratio and longer stroke (the gasoline takes longer to end the burn). a minimum of it is my understanding on the familiar modifications.

Answer 7

Compression Ratio Difference.
CC Different
One is using fuel and the other one diesel
Bore size is different
Method of starting different.
If under cold weather, the later one need heater
One is using spark plug and the other using compression
..... lots of different tehnically and cannot explain in a short context here. However the above is the general one

Answer 8

IN spark ignition engine... fuel air mixture in the engine is ignited by spark plug.... (in Petrol Engine)

In Complression ignition engine... fuel air mixture in the engine is ignited by ... heat generated by compression cycle... (In Diesel Engine)

Answer 9

spark plug is used to ignite the fuel mixture in S.I engines where as it is done by the high compression of the air in C.I engines...

The compression ratio is about 6 to 8 in S.I engines and 15 to 18 in C.I engines....

Pollution is less in S.I engines where as in
C.I engines the fuel is not fully burnt and so the exhaust gases contains some unburnt hydrocarbons....

In C.I engines the noise during operation will be more and in S.I engines it will be less...

Pick up(attaining high rpm in short period) is better in S.I engines...