AbstractRecently the requirements imposed on parts in the valve train have significantly increased and different trends are apparent for different fuels. These fuels can be defined as conventional fuels, heavy fuels, and (natural) gas. For conventional fuels, no major differences exist between truck and marine engine applications. Owing to an increase in peak pressure and process temperature, new designs and materials are required in these fields of application. For heavy fuel applications, corrosion presents a continuing problem because of further increasing temperatures. Improved materials, surface protection, and heat transfer could reduce problems such as seat burning and corrosion on valve stems, valve heads, and guides. Varying compositions of natural gas and problems with the mixture control require the optimisation of the tribological system of valve seat–valve seat insert and an improvement in the behaviour of valve materials at elevated temperatures. Both technically and economically there are many problems to solve. This paper addresses the techniques and results of improvement and optimisation, for example, finite element analysis and test facilities, improvement and optimisation of valve steels, and the surface protection, heat transfer, design, and interactions between valve stem guide and the valve seat-seat insert.MST/3156