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Determination of knock start for any engine tuning remains a difficult work for many engine manufacturers. This study investigates different combinations of existing knock indices in order to produce an upgraded indicator easier to calibrate. Experiments were conducted on a single-cylinder gas engine bounded to combined heat and power (CHP). Effects of spark advance, volumetric efficiency and equivalent ratio are studied under constant speed operation. The ratio IMPO / MAPO (with IMPO defined as the Integral of Modulus of Pressure Oscillation and MAPO as the Maximum Amplitude of Pressure Oscillation) is proposed as a suitable indicator. In any engine setting, it remains constant under non knocking conditions. When knock occurs, a model deduced from dimensionless analysis allows to determine the oversteps of Knock Limited Spark Timing from IMPO / MAPO measurements with an accuracy lower than 1 CA.

This study focuses on the development of a simulation software able to predict the car cabin blown air temperature. This software describes the fluid circuits (water, oil and air) and the engine blocks using the nodal method. It aims to enhance the global knowledge of the equipment suppliers in the thermal management between the engine and the rest of the car. A new correlation for the prediction of the engine heat losses is proposed. This correlation predicts the indicated efficiency as a function of engine settings and parameters, obtained from a statistical study. This leads to develop a reduced combustion model, which combined with the simulation software, will offer a real-time running prediction tool.