im planning on giving my 12A a huge streetport and instead of leaving at one racing beat exhaust, i want two - one for each rotor . however, this presents a problem - headers. not sure what i should do. any insight is appriciated.

 

your going to needa custom header..i havent ever seen one thats dosnt connect 2-1...i bet it has ben done seartch.

 

No, the Racing Beat street port header doesnt collect. It stays seperate all the way into the muffler. So, if you wanted true dual all the way out, just get the street port header, then have custom exhaust made with two mufflers. Or, if you have the big money, get the header AND mid section (with the two presilencers, one for each), and then just have the rest fabbed to have two seperate mufflers.

~T.J.

 

also a very nice idea

 

I have the street port exhaust on my car. And as TJ says: it is uncollected right to the muffler. So if you want a true dual, all you need is to get the first part, and then fix some mufflers and pipes to it. But where the hell is the second muffler going to be put???

 

I wanted to get one of those dual exhaust systems but i have been reading up somewhere that it's actually better if the exhaust does collect, towards the back of the car i believe.

 

There's some discussion about that. With a piston engine they need to collect, that'd be best. But with a rotary I keep hearing different stories. Check out Mazdatrix webpage, they offer a true dual system for the FC. Check this for details: http://www.mazdatrix.com/r-ex86nt.htm
System is true dual, and gives 28% power gain on FC.
Basicly you could expect simular results on a first gen, I think, but again: wher to put the second muffler. I'd go street port system. It's easy to install, very effective, and really good quality (RB)

 

As TJ puts it... I must have big money! hahaha

 

why does a piston exhaust need to collect? now that i think about it maybe my idea is not so good. if you have too big of an exhaust, wouldnt the velocity of the exhaust gases drop, and you would lose power because with a ported exhuast you want maximum exhaust velocity so at the end of the exhaust stroke, the intertia of the gas creates a partial vaccum in the engine, which sucks in more air on the intake stroke. you cant have to small of and exhuast either, obviously - it would be too restrictive. you need something just right for your application, big enough to have minimal restriction, but small enough to have maximum velocity. the same reason you dont want to big or too small of a carb. that would be a calculus problem, i wonder if thats how racing beat figured out how big to make their streetport exhaust. i might just stick with the normal one. ill do some more reasearch.

 

int the rest of the world, Headers are called "extractors". That's exactly what they do. As one exaust pulse goes through the system, as it moves, it creates a vacuum for the next exhaust pulse to go through faster.

Personally, I like them collected, at the rear axle. Supposedly, the farther back they collect, the more the powerband moves up in the RPM range.

That's why the "Street-Port" exhaust collects so far back, rather than right after the header (as per the stock port header system).

On Peripherals, they collect at a megaphone exhaust for best perfromance, although the power is at very high RPM.

 

i am wondering why you get more top end when it collects farther back...i will make my best guess and u tell me if im right...

when it collects farther back the vaccum created is relatively large and runs through most of the exhaust, which gives time for the exhaust gas to pickup speed. however, at low rpms, the exhaust gases dont have enought velocity to create a large enough vacuum thought the length of the exhaust, so if it collects closer there is a smaller area so the low rpm gases can create a good enough vaccum, but if it collects closer, the short length of vaccum becomes restrictive at high rpm, preventing the exhaust from reaching its max potential velocity.

 

if you want duals you have to move the gas tank, i know a guy who did it.

 

No you don't, you could run them both on the side the exhaust is normally on.

 

you could...but it would kinda defeat the purpose wouldn't it?

 

No, the purpose of duals is to actually have 2 pipes all the way from the engine to the rear, it shifts the power band to a different rev range compared to a collected system. I don't know if it gives more or less power than a collected system, since I've never tried running 2 pipes all the way back.

The purpose is NOT to make it look "cool" having exhaust tips on both sides of the rear or the car.

 

I have the streetport exhaust on my car, and it is without a doubt, one of the best sounding things I've ever heard. I love it.

 

CHEF_EG_1, what about performance? anything you dont like about it? im wondering because im going to be trying to extract as much power as possible from a streetported 12A n/a. i want to break 200hp and im wondering once you get up that high if the rb system becomes too restrictive.

 

The RB Streetport header and center section are GREAT. The powerpulse muffler flows much better than stock, but it is a little restrictive compared to some other mufflers. It has a very nice sound to it and is a quiet muffler, but if you want all out power, get the RB streetport header and center section but have it collect to 2.5'' pipe and put a straight through 2.5'' stainless muffler on the rear.

 

so the streetport header and center will flow good enough for 200hp+ ? any certain straight through muffler you would recommend?

 

dp

 

I've been using a 2.5'' apexi n1 style I got off ebay for $70(www.meganracing.com). It's full stainless, easily handles the rotary's heat, and has a 2.5'' hole straight through it. I don't really like the 3.5'' tip on it, I'd rather have it just be 2.5'', but oh well.

Any one will work really, as long as it's full stainless and straight through, it will be fine.

Here's a few that work:
http://www.jegs.com/cgi-bin/ncommerc...26&prmenbr=361
http://www.jegs.com/cgi-bin/ncommerc...67&prmenbr=361
http://store.summitracing.com/produc...earchtype=ecat

 

It's the other way around. Pressure wave tuning dictates that increasing the length of a set of headers tunes the powerband for a lower rpm. I think Paul Yaw said that the optimum collection length for a stock port would be about 1m past the back of the car. I've also seen pp's that have been tuned for very high rpm and they had really short headers on them.

 

revhed, can you explain why?

 

I think it is because of the time between exhaust pulses. At a lower RPM the exhaust pulses are farther apart, so there is more time between exhaust pulses. The pulses are longer, so collecting later helps them extract eachother and keep exhaust velocity up. At a higher RPM, the exhaust pulses are closer together, much less time between pulses, so collecting early helps them extract eachother and keep exhaust velocity up.

That's just my guess though, could be wrong. Also, I suck at trying to explain things, my words make a lot more sense to me than anyone else....

 

Yes..,. I noticed HUGE performance gains with my streetport exhaust.


With my old exhaust (RB road race header, welded into a single 2.25" pipe, into 2 glasspacks, with leaks everywhere), I could hit about 30mph in first gear, 55 in second, and over 90 in 3rd.

After installing my RB exhaust... I was able to hit 42 in first gear, 71 in 2nd gear, and WAY over 90 in 3rd gear. Probably close to 110. The sound is SOOOOOO smooth, and it helps the power delivery TREMENDOUSLY. I really wish that my car wasn't wrecked right now, because I wanna go out and drive it, and hear that exhaust again.