Hi I'm Patrick.I used to have a 2004 RX-8 that I sold to my oldest son.
We are in the process of replacing the engine now and have come to get rotary specific information on things we do not understand about it.

The RX-7 Forum has a lot of technical information that applies and is very helpful on our RX-8

one of the thoughts we have been thinking during this whole Renesis replacement craziness is to replace it with a 13b next time around to make it a lot easier and simpler to work on, and potentially supercharge it.

My son likes turbos but being fairly old school myself and having built many two stroke racebikes over the years, I feel a supercharger is much better suited for the rotary from what I have seen. After all, the rotary engine operates very much like a piston port two stroke motor.

My other sports car is an Alfa Romeo Spider.

 

From picking my son's brain on this topic, it seems a turbocharger might be a better option because of the excellent exhaust flow generated by the 13b.

 

On the Two Strokes, we use expansion chambers to primarily excavate the burnt combustion, with the opening cone. The closing cone is used as a reflector to push some of the excavated gasses back in. The reason for the closing cone on a two stroke and not an outright megaphone is because of the overlap of the exhaust and the transfer ports. when designed correctly, the opening cone will draw un-burnt air from the transfer ports out the exhaust. then when the piston rises enough to cover the transfer ports the closing cone pushes it back in, effectively raising the air/fuel charge density.
Since there is little to now overlap on a rotary, my theory is that you would want the megaphone part of the exhaust to excavate the burnt charge but not the closing cone.
A turbo charger would be like the exact opposite of a megaphone.

I believe Norton used megaphone exhaust on their rotary racing motorcycles.

 

Hey Patrick! Fancy meeting you here. I'm working on my FD build now and needed to pop over here for a bit.