Which engine is best to supercharging CI engine or SI engine ?
What is SI and CI engine ?
SI stands for SPARK IGNITION, means SI engine are those in which spark plugs are present to ignite the fuel.
for ex: Petrol engine.
CI stands for COMPRESSION IGNITION where highly compressed hot air is used to ignite the fuel rather than using a spark plug.
For ex: Diesel engine
What is Supercharger
A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.
So what happened when SI engine is supercharged:
In SI engine supercharging is mostly used in racing cars or air craft
When SI engine is supercharged it's volumetric efficiency increases and so the intake temperature also increases. This increase in pressure and temperature reduces the ignition delay and flame speed increases.
So for this reason lower compression ratio is acquired in engine and sometime spark time is delayed.
This is because by supercharging temperature and pressure increases which results in pre-ignition of fuel and knocking.
Another thing can be noted as SI engine uses more fuel when supercharged.
Supercharging in CI engine:
CI engine has far more advantages, as when CI engine is supercharged temperature and pressure increases and reduction of ignition delay, this high pressure rise results in smooth, quieter and better combustion.
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.
Conclusion:
So the conclusion is there are many problems in turbocharging of SI engine which can be fixed but requires a highly skilled person.
So CI engine (Diesel engine) have more advantages. Unlike the SI engine, the CI engine does not suffer from combusiion limitations and have much more advantages.
@afzal-anees