13b na -> low compression rotors?
 

Trying to figure out how I can strap at 12 inch Camden supercharger I bought cheap on to my 90 rx7 na vert. I know its a no go with the 12:1 compression, but is it possible to replace the rotors with the 9:1's from a turbo, or to bore mine out or something? Already been through a porting and rebuild, intake, exhaust, got the power fc, but that supercharger is just sitting there! Any ideas? And nobody say "go turbo"!

No Mazda rotary ever had 12:1 compression.

From my experience with Roots style blowers on piston engines, they are mainly for looks. The efficiency is horrible. I haven't seen one where you wouldn't be better off performance-wise just having an N/A build.

I'm speaking of Roots blowers, not Eaton or screw-type superchargers. The latter are compressors, while Roots blowers are air beaters.

Hmm. Don't know where I got 12:1. 9.4:1 I'm seeing vs. 8.5:1 for the turbos. My bad. Well, apparently it can be done without bursting the seals! (Come on RA 3mil's!) Point taken on the roots type peejay, but I'm maxed out @ 200whp na, so I'm gonna try it. Looks like they sell the intake manifold I need. I'm hoping to keep it 3hunna. Let you know how it goes!!!

I think what is limiting your power is not the rotors, but the supercharger.

Besides, your going to loose some low end with lower compression rotors, plus having to drive the supercharger. I believe that style supercharger exponentially looses efficiency after a certain amount of boost. I remember reading 7psi or so

You might get 230HP with that ancient and poorly designed supercharger.