Hi Mark,
Thanks for that info. I was thinking about trying a cast iron housing and rotor to start off with - no chrome or any other coatings. I'm thinking about then using aluminium end plates and steel apex seals. I'm fully aware that this combination probably wouldn't be too durable, but if I can just get something to run, I can then put more time into the materials on the next engines. At least with CNC, I can make lots of the same part without boring myself to death.
Regards
Warren