In spark ignition engines, the primary heat transfer mechanism from the cylinder gases to the wall is convection, with only 5% from radiation. Using a Newtonian model, the heat loss to the wall is given by:

Q = hA(Tg-Tw)
         The surface area of the cylinder can be determined from the slider-crank model.                 M = molar mass of the fuel/air mixture
                m = mass of the fuel/air mixture
               = universal gas constant
          Using the relationship, r = V1/V1-Vd: