Global and LDA Steady Flow Measurements in two High-Performance I.C.E. Head Configurations

Global mass flow rate analysis (in terms of discharge and flow coefficient) and LDA measurements around the valve curtain (in terms of mean and rms values) have been used in order to compare the fluid dynamic efficiency of two different four-valve high-performance engine head configurations. The two engine heads have the same bore and valve diameters, but a slightly different valve position and valve stem inclination. Local velocity measurements have been shown to be very useful to highlight the different contributions which lead to variations in global mass flow rate. More specifically, results have clearly shown that the distance between valves and cylinder wall is a critical factor for head permeability and that the distance between the two intake valves as well as the valve stem wake also play an important role.