Influence of atmospheric conditions on s.i. engine performance and comparison of different correction-factors

A large number of tests have been carried out on a s.i. engine, equipped with an injection and ignition electronic system, in a climatic/barometric chamber with a roller dynamometric bench test for the evaluation of temperature and pressure effects on engine power over a wide range of variations. The converted experimental results have then been compared with those obtained in standard conditions by means of three different correction factors. As the range of pressure and temperature variations was very high, a different procedure was used in order to convert the obtained data to specific standard atmospheric conditions. Such a correction nevertheless requires not only the knowledge of total engine mechanical efficiency, but also the two contributions which are respectively dependent and independent on atmospheric conditions. For this purpose a specific method has been proposed and the final comparison of the converted experimental data with those obtained in standard conditions shows a better agreement