Friction power
Analysis of energy transfer in automotive engines

As shown in figure 2 (in energy form), the power transmitted to the piston by the combustion of the fuel mixture, the indicated power P _i , is not entirely available on the drive shaft in the form of effective mechanical power P _e . The losses corresponding to the transition between indicated power and effective power are generally referred to as friction losses P _tf .

As we explained earlier, it's easier to talk in terms of mean pressure, so for friction we'll talk...