The results of a predictive modelling study on the transient load response of a heavy-duty turbocharged diesel engine are presented in this paper. The model is based on a wave-action calculation code, whose input parameters are managed by an external module, which updates their value according to the changing engine running conditions. The transient operation aimed at is a load increase from idle to full load, at constant engine speed. Several modifications to the engine design have been simulated: valve size and timing, inlet manifold dimensions, insulation of the exhaust manifold, and turbine design. The response of the engine operation to these modifications has been evaluated by means of the transient duration and of the evolution of relevant engine parameters.