Here is a link i found interesting, Performance auto parts, turbochargers,Central Florida Second product from the bottom of the page. I can see a few good benefits in using aluminum rotors as opposed to the standard iron rotors from the Mazda factory. 1. Less weight is always better in an aircraft of any kind. 2. If you retain the same rpm that you are currently using in you standard rotor motor, the engine will vibrate a lot less, adding to the durability of the entire aircraft. 3. The excellent heat properties of aluminum over iron (I think the oil system would play a much larger roll in the cooling of the motor and probably need a greater size cooler) One issue I see is the greater expansion of aluminum will give minor wear issues during warm up due to clearances, though this is easily solved by using aluminum with a higher silicone content. You will also need to replace or balance the counter weights. There are so many pros and cons of using Aluminum rotor and i am looking forward to your input.