coatings and treatments

[RETed]

Originally Posted by rgould

2) the rotor does not ride against the side plate so it does not need hardening. Ceramic coating is a better choice to help keep the excessive heat on the rotor face and to help control oil temps.

Be very careful about this...
There is a right way and a wrong way for these coatings.
In general, metal sections are used to conduct heat (away).
Putting coatings on the wrong surfaces can increase (internal) heat (into the cooling and oil systems).
Mazda engineers have documented that the rotary engine oil system takes care of 1/3rd of the heat (dissipation) from the working engine.

3) I have been involved with cryoed brake rotors on all out race cars and for some reason they last longer than ones not cryoed so it does something good to the metal.

It's the conversion of martensite and austenite crystals within "steel" alloys.
http://en.wikipedia.org/wiki/Cryogenic_hardening

4) shot peening uses small steel shot like steel bbs to beat the metal surface to remove internal stresses.

You should remove the word "internal".
This is more a surface treatment, and it converts tensile stress to compressive stress.
It is also not recommended for critical clearanced surfaces.
http://en.wikipedia.org/wiki/Shot_peening


-Ted