In admission we use nickel-aluminum bronze, aluminum bronze, phosphor bronze and beryllium copper.
in the exhaust, cast iron, phosphor bronze and beryllium copper
Beryllium Copper:
Beryllium copper that we used in an engine with titanium valves in the intake, in this engine the valve seats used the same beryllium copper material, tests with the other materials showed superior wear on the titanium valve compared to beryllium copper.
I don't have conclusive heat transfer efficiency tests for the materials listed, and therein lies my interest in information from practical experiences.