Heat transfer coefficients were obtained from measured instantaneous surface temperature and heat flux on all the combustion chamber walls of a direct injection diesel engine. When heat transfer coefficients based on the experiment were compared with those calculated from Eichelberg′s and Woschni′s formulas, it was clearly shown that rates of temporal change were considerably different in some portions. In this paper, causes of the difference are discussed so that insights useful for proposal of a more widely applicable formula with higher accuracy can be obtained.