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Valve train system is one major contributor to engine overall friction loss and is approximately 30% of total engine friction at lower speed and approximately 20 % at higher engine speed. Valve spring loads (preload and working) are proportional to friction loss of valve train. To optimizing the valve spring design main requirement is valve train perform it function safely at maximum engine cutoff RPM with minimum preload and working load. Robustness and frictional power loss are contradicting requirement, robustness demand high stiffness spring for better valve jump and bounce performance with dynamic safe valve spring design, on the other hand low frictional power loss demand for use of low stiffness spring. To optimize the valve spring stiffness for meeting both the requirement we need accurate prediction of valve spring in design stage and good correlation with testing data to reduce the number of iterations.

To achieve acceptable valve train lubrication with low viscosity oil is challenging. Understanding the effect of valve train design parameter on valve train lubrication is important. In this study rocker arm valve train mechanism is analyzed to check the influence of valve train design parameters on lubrication at cam and rocker face interface. In valve train lubrication, lubrication oil film thickness play important role in valve train wear and friction. Main objective is to maintain acceptable oil film thickness at peak valve lift and minimizing the duration of critical minimum oil film thickness at cam flank to avoid wear at cam/ roller rocker follower interface when using low viscosity oil. Cam nose wear effect the engine performance and wear at cam flank change the dynamic characteristics of valve train.