1. A soft-computing method for establishing the dissipation law of the heat in a diesel Common Rail engine, in particular for establishing the dissipation mean speed (HRR) of the heat, wherein the system set-up comprises the following steps: choosing a number of Wiebe functions whereon a dissipation speed signal (HRR) of the heat is decomposed; applying the Transform Ψ to said signal; realizing a corresponding neural network MLP by means of an evolutive algorithm; training and testing said neural network MLP.