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By using diesel engines with high torque and instant response as offered by those with a suitable supercharging system, it proves possible to shift the average operating point close to the engine efficiency optimum. Computer analysis confirmed by chassis dynamometer tests of two car sizes equipped with Comprex charged IDI engines show a potential improvement in fuel economy of 19 - 26%. Comparison is made with a NA engine having equivalent road performance as defined by the acceleration rate.

From a comparison of different methods of supercharging it becomes evident that the pressure-wave-supercharger is a highly efficient device of improving fuel economy of automobiles without loss of performance. Tests on a chassis-dynamometer and computer simulations show that it is possible to save up to 25 % of fuel and at the same time to reduce the emissions of exhaust gases considerably by “Down-Sizing” and “Down-Speeding”.

The main components of vehicle diesel engine emissions are nitrogen oxides and particulates. The emissions concept adopted for pressure-wave supercharging with controlled EGR and particulate trap, focuses on both components. In conjunction with electronic EGR-control the spontaneous response of the supercharger achieves minimum deviations from optimum air excess values, even during transients. In the US city cycle an NOx reduction to 35 % of the reference emission, without sacrificing fuel economy was established. Featuring a particulate trap arranged between engine and supercharger this system increases the regeneration probability and as a result of the improved supercharsinp, efficiency achieves satisfactory transient behavior, Catalytic coating of the rotor constitutes an additional means of reducing emissions.

The Comprex is the first pressure wave machine to reach series maturity. The direct contact between the media exhaust gas and combustion air permits a transfer of energy at high efficiency. Because of its basic characteristics, the pressure wave machine is especially well suited for the supercharging of passenger car diesel engines. It exhibits a spontaneous response and achieves high supercharging rates over a wide operation range, thereby contributing to an improvement in fuel economy. For the purpose of reducing emissions, it offers a simple means of providing EGR, thermal conditioning of the charge air, catalytic aftertreatment of the exhaust gas in the cell wheel and a compact particulate trap arrangement.