Question

Comparison between ci engine and si engine

Answer 1

Basically SI engines work on Otto Cycle and CI engines on Diesel cycle
2. SI engines use gasoline as fuel and CI engines use diesel as fuel.
3. SI engines use spark plugs and CI engines don't this is because the compression ratio of SI engines is small and the temperature developed is not high enough to start the combustion and so spark plug is used to initiate the combustion once the initial spark is generated the flame front takes care of the rest ,whereas in a CI engine the temperature generated is higher than the ignition temperature of diesel due to high compression ratio and so a spark plug is not needed.
4.The torque generated by CI engines are very high when compared to their counterpart SI engines this is because the CI engines at high compression ratio and so the piston travels far more distance into the cylinder and so the radius of crank also increases ,since torque is cross product of force and radius therefore this increase in radius causes an increase in torque ,the above is one of the many factors contributing to high torque of CI engines,and this is the reason why almost all the trucks and heavy vehicles use CI engines and passenger vehicles and bikes use SI engines.

Answer 2

Answer:

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.