With the modifications brought to the combustion chamber environment (cylinder, cylinder head, valves…), the contact surface between valves and valve seats have been investigated to check if the modifications help to reduce the wear observed on engines in service and improve the reliability of the valvetrain. The results show that the wear have been largely increased on the core engine demonstrator compared to measurements made on in-service engines. This excessive wear can come from the modifications done on valves themselves or from the evolution of the combustion chamber conditions (change of cylinder, change of cylinder head...) and will need further investigations.