How much power could you get out of a 13B Rotary for a s4 87 RX7 without putting a turbo on it?

 

With a fresh rebuild (using s5 rotors and intake), a large streetport, CAI, and full exhaust with good header maybe 160 at the wheels. With a standalone and a good tune, 180-190. Without a rebuild, you aren't going to get much. Teh only things to add power without a rebuild is an intake an exhaust which doesn't provide huge gains.

 

How much power do you want? Practically speaking without nitrous we are talking about 350HP with a peripheral port.