I came across this today, which contains patent information from Mazda concerning rotor housings. Maybe this stuff is common knowledge to some or even most, but I had little knowledge of it and it was quite interesting to me. Talks about a lot of different ideas that Mazda used to produce the 86-95 rotor housings, and the varying hardness of the materials used during production. For instance, Mazda used different hardness values in the chrome plating on the inner surfaces on the housings. In the areas around the spark plug holes, Mazda actually softened the chrome plating using a laser to avoid apex seal wear. The patent info goes on to explain hardness values for housings and apex seals, and provides diagrams for the ideas. Maybe someone will get some enjoyment out of it.

Patent US4755116 - Rotor housing for a rotary piston engine having softened areas surrounding ... - Google Patents

 

I have read through a few of these, Mazda did some great work concerning materials as well as studying oil retention which I got to see first hand. I had a junk-ish housing I used for display, the housing got cleaned and painted. I put it in my oven to bake the paint and when I pulled the housing from the oven I could see it had "sweated" some oil and a good amount actually.

 

Very interesting read indeed. Anyone have anymore of this type info?

 

yes this is another reason why resurfacing housings is not as good as new parts using the original process. And the stock housing designs are old. I'm definitely looking forward to hearing about the new materials Mazda is cooking up for the new rotary if it ever sees production.