ice as in internal combustion engine, sorry for confusion 1. The problem statement, all variables and given/known data I'm given an engine operating on the dual cycle and asked to find the thermal efficiency and the mean effective pressure. the compression ratio is 18:1, the temperature at the start of the compression 300K and the pressure is 100kN/m^2. the pressure ratio for the constant volume part of the heating process is 1.5:1 and the volume ratio for the constant pressure part is 1.2:1. im taking gamma to be 1.4. 2. Relevant equations compression ratio = rv pressure ratio = a volume ratio = rc gamma = y eff. = 1 - (1/rv^(y-1))[((a.rc^y)-1/((a-1) + ya(rc-1))] 3. The attempt at a solution I found the efficiency to be 67.9% but now i need to find the mean effective pressure and im stuck. obviously i know its work output over swept volume but im at a loss to find either for the dual cycle. help please.