Explain the term w.r.t. I.C. engine............

( i ) Mean effective pressure – Defined as the average pressure acting on the piston which will produce the same output as is done by the varying pressure during the cycle.

( ii ) Cut off ratio – Fuel is injected into combustion chamber where only air compressed and is at high temperature. Fuel is injected for a duration of time, say T. The piston would not have reached the bottom dead centre in time T. The fuel is cut off when the volume is, say V2. The clearance volume is V1. The ratio V2/V1 is cut off ratio.