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What is the difference between a SI engine and a CI engine?
An SI engine ignites the fuel with a spark (SI = Spark Ignition) whereas the CI engine ignites the fuel with heat generated from compression (CI = compression ignition)
What are the supercharging limits for si engine and ci engine?
Limit of supercharging in si engine (1) knocking tendency in si engine increases with increase with temp pressure density of charge , mixture strength (2) compression ratio of engine needs reduced with supercharged engine but the reduced compression ratio reduce the power output output & thermal efficiency of engine with increase in s.f.c WHEREAS Limit of supercharging in CI Engines are mainly due to the thermal stresses and increased gas loading. Due to this, the heat generation and heat transfer increases and there is a greater tendency to bum the piston crown and the seat and the edges of exhaust valve. Increasing the valve overlap in supercharged engines solved this problem.
Why si engines are quantity governed engines and ci engines are quality govrned?
All engine are whether CI or SI are quantity governed. what is quality governed?? You have discovered it or wht??
Why for the same power CI engines are larger and heavier than SI engines?
SI is SPARK IGNITION - Otto (4-stroke) and Day (2-stroke) cycle CI is COMPRESSION IGNITION (DIESEL) also in 4- and 2-stroke variants The SI spark plug is timed to start combustion at the ideal moment, usually some degrees before the piston reaches the top (TDC or Top Dead Centre). The burning mixture then drives the piston down for the power stroke. The CI fuel is injected (sprayed) into the cylinder at the ideal moment - this too is usually some degrees before TDC, and the red-hot air in there then starts the fuel burning. This then drives the piston down for the power stroke. SI is limited in maximum compression ratio (the amount the air or mixture is compressed as the piston rises in the cylinder), or it can start to behave like CI (Dieselling). CI uses the highest compression ratio possible to improve ignition - and - improve efficiency too... The expansion ratio is the inverse of the compression ratio, and the more that the burning gas is allowed to expand whilst doing work, the better the efficiency. CI is also an 'excess air' cycle, potentially. A full cylinder of air is compressed each time, and the amount of fuel injected is varied to change power - this is beyond the lean burn that can be achieved with SI.
What is peak pressure in si engine?
30-40 bar peak pressure
How the knocking differs of SI engine with CI engine?
In SI engine knock occur due to spontaneous ignition of end gases , as propagating flame compresses the mixture causes high temp & pressure reaction take place in end gases that burns rapidly with high pressure peak called knock. Where as in CI engine knocking or detonation occur due autoignition fuel & air not mixed homogeneous prior to combustion.pressure peaks of knock come before Top Dead Center(TDC) in CI engine where as in SI engine it comes after the TDC.
What is the difference between a SI engine and a CI engine?
An SI engine ignites the fuel with a spark (SI = Spark Ignition) whereas the CI engine ignites the fuel with heat generated from compression (CI = compression ignition)
What is SI engine and CI engine?
An SI engine is a spark ignition engine. A CI engine is a compression ignition engine. SI engines use spark plugs to ignite fuel in the combustion chamber. CI engines use compression in the combustion chamber to ignite the fuel.
What are the supercharging limits for si engine and ci engine?
Limit of supercharging in si engine (1) knocking tendency in si engine increases with increase with temp pressure density of charge , mixture strength (2) compression ratio of engine needs reduced with supercharged engine but the reduced compression ratio reduce the power output output & thermal efficiency of engine with increase in s.f.c WHEREAS Limit of supercharging in CI Engines are mainly due to the thermal stresses and increased gas loading. Due to this, the heat generation and heat transfer increases and there is a greater tendency to bum the piston crown and the seat and the edges of exhaust valve. Increasing the valve overlap in supercharged engines solved this problem.
Why si engines are quantity governed engines and ci engines are quality govrned?
All engine are whether CI or SI are quantity governed. what is quality governed?? You have discovered it or wht??
What are si and ci engines?
SI engine means Spark Ignition Engine where combustion products(air,fuel)are ignited in combustion chamber by means of spark from spark plug which is located on cylinder head..CI engine means Compression Ignition Engine,here combustion is take place by means of compression..
Why CI engines are used in trucks and other heavy vehicles but not why SI engine?
Compression ignition (CI) engines use diesel is as the fuel, while spark ignition (SI) engines use petrol. SI engines are lightweight and achieve high speeds while diesel CI engines although heavier and slower engines, are more robust and have a higher thermal efficiency. Their robust build (and fewer parts) makes diesel CI engines ideal for heavy machinery.
How many cam in 4 stroke engine?
for SI engine 2 cams will be provided......,for CI engine 3 cams PROVIDED for opening of inlet,exhaust valves and operating of fuel injector...ok got it
Where is fuel and air mixed in an engine on a newer car?
Mixing of fuel and air depends on type of the engine whether SI or CI. In carburetted versions of SI engines the charge mixes in the carburetion chamber and the mixture is let into the engine. There are direct injection SI engines(GDI) where the injection takes places at various stages of charge compression stroke. In CI engines the fuel is mixed with air in the combustion chamber itself. It is to be borne in mind that these mixing phenomenon are the same be it a new or old car.
Why for the same power CI engines are larger and heavier than SI engines?
SI is SPARK IGNITION - Otto (4-stroke) and Day (2-stroke) cycle CI is COMPRESSION IGNITION (DIESEL) also in 4- and 2-stroke variants The SI spark plug is timed to start combustion at the ideal moment, usually some degrees before the piston reaches the top (TDC or Top Dead Centre). The burning mixture then drives the piston down for the power stroke. The CI fuel is injected (sprayed) into the cylinder at the ideal moment - this too is usually some degrees before TDC, and the red-hot air in there then starts the fuel burning. This then drives the piston down for the power stroke. SI is limited in maximum compression ratio (the amount the air or mixture is compressed as the piston rises in the cylinder), or it can start to behave like CI (Dieselling). CI uses the highest compression ratio possible to improve ignition - and - improve efficiency too... The expansion ratio is the inverse of the compression ratio, and the more that the burning gas is allowed to expand whilst doing work, the better the efficiency. CI is also an 'excess air' cycle, potentially. A full cylinder of air is compressed each time, and the amount of fuel injected is varied to change power - this is beyond the lean burn that can be achieved with SI.
What is CI unit of speed?
If you mean "SI", that would be meters/second.
Why can a CI engine be more easily pressure charged compared to SI engines without fear of detonation?
because it only compresses/pressurized air (without the mixture of fuel)
