This paper presents an investigation into the potential efficiency and performance improvements in an internal combustion engine by changing the mass and stiffness of valve train components, specifically the mass of the valve and the stiffness of the valve spring. Changes in valve mass affect the dynamic response of the valve train, so changes in other components must be made to maintain reliable and efficient engine operation. In order to quantify the potential benefits of lightweight engine valves, a dynamic model of the complete valve train system was developed. This model was experimentally validated on a motored engine in which the valve motion was measured for different combinations of valve mass, spring stiffness and engine speed. This paper describes the development and validation of the dynamic model, and discusses the effects of varying the valve mass and valve spring stiffness. It was found that a 75% reduction in the mass of the valves (as expected through the use of fiber reinforced composites) could reduce the maximum camshaft drive torque and frictional power by about 60–70%.

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