Materials Questions
 

Maybe a dumb question, but I would like to know the answer:

What is the material of the side housings (side plates) in Mazda 12a/13b/20b engines? Is it steel or cast iron? I'm guessing iron, but someone recently told me they were steel.

Also, does anyone know what grade of aluminum the rotor housings are made from?

Just curious...
Cheers,
-Bug