LDA Investigation on Valve - Wall and Valve - Valve Flow Interaction in High-Performance 4-Valve I.C.E. 2001-01-1309
The fluid dynamic efficiency of two different four-valve high-performance engine heads has been compared both in terms of global mass flow rate and in terms of local velocity distribution around the valve curtain, by means of LDA measurements. The two engine heads have the same bore and valve diameters, but a slightly different valve position and valve stem inclination. Results clearly show that valve-wall distance is a critical factor for head permeability and that even marginal variations in valve position and inclination lead to appreciable differences in flow pattern and total flow rate.