how to gain HP from na s4
 

this is my plan, rebuild motor, bridge port, e85 conversion, and tune.
how much hp gains do yall think?

depends on the bridge, and the intake you are going to run.

stock intake manifold will really limit you

Cheap plan is-
TII front/rear side housings, 4 port Holley 4150 style intake manifold, simple 4150 throttle body w/ no injector bungs, Bosch EV14 2,000cc injectors/aftermarket rail in primary location for fuel and Megasquirt for ECU, headers, 1 piece carbon apex seals, clearance rotor sides.

If you do a big j-bridge (basically a p-port that uses the stock runners in the side housings) you can run a zero pressure cooling system with 100% PG coolant (like Sierra Pet Safe) to you don't spring a leak into the intake ports as easily.

If you do a big j-bridge you might get more low end power/response without much sacrifice up top if you fill in the stock port area and just keep the bridge/portion cut into rotor housing.



https://cimg3.ibsrv.net/gimg/www.rx7...2f9b501eb7.jpg

https://cimg0.ibsrv.net/gimg/www.rx7...9785bd19a8.jpg


Another nice option is instead of a bridge do a semi-peripheral port with the same 4150 style semi-p-port intake manifolds. This simplifies sealing the cooling system between the side housings and rotor housings and allows stock 2 or 3 piece apex seals.



https://cimg5.ibsrv.net/gimg/www.rx7...e5707fb6d7.jpg