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In this paper the 1-D modeling of flow through the assembly of valve and port in internal combustion engines is discussed. Three dimensional effects and flow losses close to the valve are accounted for through the experimental effective area, determined at a steady flow bench. The steady flow bench is standard equipment, widely used for engine design and development. The classic method is adequate to the purpose as long as the objective of measuring the effective area is a comparative process for the experimental improvement of the flow through the valves. On the contrary, if the effective area is used for engine cycle simulation, the experimental results must be considered with care. It is demonstrated in this study that, for the outflow from a cylinder to a valve, standard experimental practice can sometimes produce a significant error on the flow rate predicted by simulation.

An automotive 3.2 liter, V8, turbocharged S.I engine by Maserati is analyzed by using integrated experimental and computational methods. An experimental activity has been carried out during the dynamometer test. Torque, fuel consumption and air-fuel equivalence ratio have been measured for several engine speeds at wide open throttle. Furthermore, cycle averaged gas pressure and temperature have been acquired in the most important engine locations. A 1-D fluid dynamic model has been set up, for the engine simulation using the WAVE code, by Ricardo Software. The modeling guidelines are discussed in details. The accuracy of the model has been assessed through a comparison between the experimental and computational results. Finally, a few simulation outputs, particularly useful for addressing the optimization process, are shown.