EpitrochoidMan

From what I've read (on this forum and elsewhere) ceramic coating your rotors seems like a great thing to do. But has anyone done this and also coated the apex seals?

Will the ceramic material wear off of apex seals? B/c if it does then you have just metal apex seals (I don't think the chips of ceramic material would do much harm in the engine) and being as carbon tends to build up on the apex's wouldn't this be more likely to cause detonation. Especially because with coated rotors they would handle heat much better than bare metal, and if you had bare apex seals they would carry more heat than the rotors. Add that to the carbon they aquire and it seems like a detonation would be more likely.

Also, wouldn't ceramic or titanium nitride coated seals be harder than the housing? Has anyone with either of these coatings on the seals had damaged housings?

I have very little experience with these rotary engines (just got my FD ) And I'm trying to learn more about them.

fdbabb

The coating they put on the rotor faces and piston tops doesn't come in contact with the housing. I'm 90% sure its different from the ceramic material, and finished differently than, the ceramic stuff the 100% pure ceramic seals are made out of. They sure look different. The face cer. coating is a flat white, the cer seals are shiny gray.

Metallury and Ceramics engineers care to chime in? Where are those Mazda engine engineers when ya need em?

Fatman0203

Why do that if ceramic seals already exisist? BTW ceramic seals and ceramic in general is VERY rough on housings and other aluminum.

badfish229

Ceramic seals cost an arm and a leg. Why would you coat an apex seal in the first place? It's like coating a piston ring, and engine builders don't do that. You might mess up the clearance between the seal and the housing surface. Your stock seals will do just fine, until you really start cranking up the boost.

Fatman0203

Exactly and if you have the money to "really start cranking the boost" then you have money for better seals. Even though (not sure about th enew 2 piece) but on the stock 3 piece seals people were doing over 20psi.

rxseven

Wait a minute guys, you can't just coat metal pieces in the combustion chamber without thinking about heat conductivity. Ceramic seals have virtually no heat expansion and therefore can be sold in one piece with tight tolerances. Metal seals on the other hand will undergo dimensional changes under high temperature. That is why it is essential for the seals to conduct heat to the housing and rotor. Putting a coating on there will greatly reduce heat transfer and the life of the motor.

BATMAN

As mentioned the ceramic coating is not for contact surface.

It serves as a heat barrier to reduce heat transfer and subsequently, heat soaking.

This will help reduce the work-load of the oil cooler.

93tourtom

Just to correct what someone said about piston rings not having coatings. Virtually all piston rings in all cars have coatings. The only exceptions are some lower compression rings being plain gray iron and some top compression rings being nitrided stainless steel (hardening process but technically not a coating). Mazda must've had a reason for not coating the apex seals since all the rings in their piston engines require coatings.