Range extender engine with very high power density, suitable for the use in a hybrid propulsion system: Virtual combustion optimization with advanced CFD 1D-3D virtual validation. The project carried out during an internship at Leonardo and it consists of the realization of a CDF simulation on the combustion of a high-performance engine equipped with a range extender. The previous and similar work was conducted by Vincenzo Bottari using a geometry and first attempt data obtained from the study of Carlos Mariani, who made a 1D model using Wave. My work is to verify the data obtained by Salvatore Chierchia, whohas been involved in improving the results obtained in the previous Mariani’s study.