I just found out yesterday that I have a front and rear rotor in my garage that both have N's stamped on them, and one is lightened/balanced, and the other is balanced. What do the N's mean, and how rare/common are those rotors? I'm keeping them for when I rebuild my engine, but I'm just curious about how rare they are.

If the N is cast into the combustion chambers they are 12A 6 port rotors. They're lighter and higher compression than the common 4 port rotors. There are less of them around but they're not that rare. I just bought 3 pairs new from Mazda.

What do you mean by 6 port? I'm kinda newish to rotary, but I plan on learning anything and everything I can about them.

I have a pair of N cast JDM 12A rotors(from junk engine) but they're from a 4-port. At least, I was told the motor was JDM when I bought it and then replace it with a 13B.

i think in the usa those are just 83-85 12a rotors, they are lighter than the older rotors by a tad.



presumably the turbo rotors have a T cast into em

Ports are the rotary equivalent of valves on a piston engine. They are what lets air/fuel in and lets exhaust out of the engine.

FI first gen motors have 6 ports, carb'd motors have 4. Four-port motors can usually take wilder porting.