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..
All engine are whether CI or SI are quantity governed. what is quality governed?? You have discovered it or wht??
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.
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.
we can use si engines in place of ci engine in trucks.. Bt as u know in trucks heavy power is required to carry such high loads.. Nd also the cost of petrol is higher than diesel so to obtain high mechanical power nd less running cost diesel engines are used..!
because it only compresses/pressurized air (without the mixture of fuel)
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.
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)
compression ignition
Intake, compression, power/combustion, exhaust. Same as a standard SI (Spark Ignition) CI (Combustion Ignition) is how diesel operates. They contain no spark plugs. The compression heats the fuel to the point of SELF COMBUSTION .
because it only compresses/pressurized air (without the mixture of fuel)
250 ci,305 ci, 350 ci, 350 ci (Diesel), 379 ci (Diesel) (1982).
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.