Peripheral port question
 

could someone explain to me why a peripheral ported motors don't lasty as long. Is It directly from the peripheral ports or is it just that nearly everyone with a peripheral ported is pushing there motors to the limit?
Also does anyone know EXACTLY what engine rotors are made of? I know It has to be some ferrous bearing metal but I don't which one/ones...

let me preface with this. i've never built a peripheral port engine and i therefore do not own one, but with that out of the way ... here goes.

they've traditionally been pretty high-strung, race-only engines, but they are being used in more domestic settings now. so i have a feeling they probably have longer lifespans in street environments these days given the current state of fuel injection and engine management.

the port doesn't change the lifespan of the engine, what shortens it are the carbon apex seals and the high rpm use.

the carbon seals, are pretty soft, and the geometry mazda chose for the engine means that wear goes up exponentially over 7000rpm.

if you built a stock port engine with carbon seals and revved it to 9k it wouldn't last any longer than the p port.

the engine rotors are made of cast iron, nothing fancy