thielepr

Like the title says What is a proper exhaust for 12A Bridge Port?

Right now our car have 163 WHP. The exhaust is a RB race header with RB style made locally mid-section and the RB street port muffler.

What is better?? single ? Dual ?? what diammeter? is it worth it on money vs hp gains??

What are you running on 12a bridge port

j9fd3s

iTrader: (3)

i don't know, and it will depend on the size of the bridge and stuff. so here are the two things to check to get it right, or better.

#1 backpressure! hook a pressure gauge up to the exhaust. go for a drive, more than 2psi of backpressure and you're loosing power.

#2. the length of the header. this is pretty simple, start with a long header, go to the dyno and start cutting it. i'm gonna use RB pipe, which comes in 4 foot sections. so with 3 i get 2x 4 footers, and 2x 2 footers. the RB header is about 26" long, so the different sections gives 26" 52" 72" and 90something. once you have those 4 dyno sheets you can pick one.

if you're really dedicated, you can try different diameters after the collector, 2.5 should be fine, but maybe 3 is better?

-Gamah

iTrader: (1)

Straight side exit behind the front right wheel, no cat, silencer, or muffler... maximum HP, minimum cost

of course, you may get a few noise tickets...

Crispin38

iTrader: (3)

On a 12A BP it at least needs to be 3 in. collected. I think the RB header and midsection is effecient but I think you just need to toss the street port muffler and buy one from rotary shack or mazdaspeed.

thielepr

It is worth it?? Power gains vs noise?

thielepr

I didn't find any exhaust at the rotaryshack webpage. Could you point me a link? Thanks

BeenJaminJames

Short answer, if you're driving on the street, hell no. The noise from an open header rotary WILL make your ears ring for hours, and can easily burst your eardrums. Drag racing/track day car, every milisecond counts as long as it's class legal. My guess is if you were building a dedicated track day car you would be experimenting with many different setups as j9fd3s mentioned.

Here you go, if you think $300 is worth the slight improvement:Clicky

PercentSevenC

That's just a $124 RB universal muffler with a piece of a pipe bend welded on.

http://www.racingbeat.com/RX7-1975-1...nts/16030.html

-Gamah

iTrader: (1)

For most, no... unmuffled rotaries are VERY LOUD.... but if you don't mind losing some your hearing you will get maximum HP.