A computer program has been developed to simulate the operational behavior of turbocharged Diesel engines under transient conditions. The essential characteristics of this program which is based upon the filling and emptying model are presented. In particular, the code considers the waste gate behavior, the charge-air cooler and the component temperatures which vary during acceleration. A comparison between computed and measured response has been made for a turbocharged inter-cooled 4-cylinder swirl chamber Diesel engine. The code has also been used to assess improvements in the acceleration behavior which can be realized by a strongly reduced mass of inertia of the turbocharger rotors, lower friction of the bearings, variable geometry of the turbocharger turbine and heat insulation of the exhaust ports and the exhaust manifold.