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 in terms of mean friction pressurepmf to study the friction power P_tf. In the remainder of this paper, we will focus solely on pmf, which is...