Light-Weight Composite Valve Development for High Performance Engines

A study is presented in which light-weight composite materials are used for an engine intake valve. This paper is an interim progress report and documents the successful demonstration of a net-shape, resin transfer molded intake valve in a running engine. A short review of a previous dynamic model is presented showing the advantages in engine performance by using the composite valves. It is shown that the use of reduced mass composite valves allows for increased engine speed and/or more aggressive cam profiles without sacrificing valve strength or stiffness while at the same time maintaining reliable operation. The use of composite materials allows for a significant weight reduction compared to more conventional materials such as steel and titanium. A brief review of the use of composite materials is presented. The development and design process for carbon fiber reinforced valves is discussed. Progress on the manufacturing and validation testing of a resin transfer molded (RTM) fiber reinforced composite intake valve is presented. A carbon-fiber composite intake valve has run in an engine at 1700-1900 RPM with no load for more than 400 continuous minutes without failure. Another valve experienced an apparent thermal/oxidative failure when run at higher speed and load. Initial thermal analysis of the failure mode is presented as well as a test plan to overcome this limitation.