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An experimental analysis was executed on a NA (Natural Aspirated) 4-stroke gasoline engine to investigate the potential of exhaust waste energy recovery using power turbine technology for light duty application. Restrictions with decreasing diameter were mounted in the exhaust to simulate different vane positions of a VGT (Variable Geometry Turbine) and in-cylinder pressure measurements were performed to evaluate the effect of increased exhaust back pressure on intake- and exhaust pumping losses and on engine performance. Test points in the engine map were chosen on the basis of high residence time for the vehicle during the NEDC (New European Driving Cycle). The theoretically retrievable power was calculated in case a turbine is mounted instead of a restriction and the net balance was obtained between pumping power losses and recovered energy.

To improve the mixing of fuel and air in the combustion chamber of current diesel engines, research is carried out regarding injectors with a porous nozzle tip, replacing conventional nozzles with a limited number of holes. Preliminary tests with porous injectors showed that further research concerning spray distribution was necessary due to non-optimal spray shapes and low fuel velocities. Therefore, spray shapes and fuel velocities of porous injectors were examined at atmospheric pressures. These examinations show that the spray shapes can be adjusted by alternating the geometries. Geometrical influences have been studied and compared to conventional injectors, showing that the fuel velocity of the porous injectors has decreased with approximately a factor of 10. Subsequently, research concerning the lifetime of porous nozzles was necessary due to premature failure.