it is fair to assume that the heat rejection from an otto cycle is typically to the ambient at a temperature tmin, the minimum temperature of the cycle similarly the temperature at which the heat added can not exceed the adiabatic flame temperature .let this maximum temperature of the cycle be t max . let us further assume that the working fluid is an ideal gas with the ratio of specific heats given by gema which is independent of temperature. Find the optimal compression ration interms of the upper ans lower temperature limits of operation. the optimal compression ratio should yield maximum specific works ans optimal compression ratio is (tmax/tmin) ^(1/2(gema-1))