In an internal combustion engine comprising a mechanical charger in the form of a positive displacement compressor connected to the engine intake duct for supplying compressed air to the engine and a turbo-compound including an exhaust gas turbine connected to the engine exhaust duct for converting energy remaining in the exhaust gas to power, the exhaust gas turbine being connected to the engine via a reduction gear drive, the mechanical charger and the turbo-compound are coupled to the engine by a common belt drive including a first belt pulley mounted on the crankshaft of the engine, a second belt pulley mounted on the shaft of the reduction gear drive, and a third belt pulley mounted on the shaft of the mechanical charger.