Custom Exhaust Build
06-21-10, 03:28 PM
#1
Custom Exhaust Build
I've decided for economical purposes, and for the fun of it, I'll be building my own exhaust. I'll be running three inch all the way back, and was hoping for suggestions from you guys for the cat and muffler combo. A friend that owned an FB had used magnaflow mufflers that were around 70$, and they sounded decent even on his 12a. With mine being a turbo though, are there any special considerations to be made? Do I need to worry about melting stuff on the cat or muffler? Do I need to buy "rotary" specific stuff?
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
06-21-10, 04:52 PM
#2
89FC
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Go 3" down pipe to a RX7.com cat, then 2.5" back to the muffler. the 2.5 will keep boost kreep down (you will still get some) for a muffler just get a style you like but don't go and buy some knock off crap, it'll just fall apart.
06-21-10, 05:10 PM
#7
89FC
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I couldn't comment much on keeping it to legal standards, I don't know what the smog laws are like in AZ, but i figured they are similar to CA. The set up I posted up should keep it pretty close to legal depending on the muffler you chose.
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06-21-10, 05:13 PM
#8
89FC
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Oh one other thing, I've learned this from trial and error. When building something from scrach make sure you do loads of planing, take your time, and have pride in your work. GL and take pics!
06-22-10, 01:43 PM
#13
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If you port the wastegate you will need a bigger gate door(which requires welding), and still you will have boost creep, it does not cure it, to rid yourself of boost creep you need a good electronic boost controller and an external gate.
If you take a look at the RB exhausts you'll see that they don't use huge piping and yet they are one of the BEST exhausts for a lightly modded turbo rotary.
Bigger isn't always better.
If you take a look at the RB exhausts you'll see that they don't use huge piping and yet they are one of the BEST exhausts for a lightly modded turbo rotary.
Bigger isn't always better.
06-22-10, 02:00 PM
#14
The Firestarter
I've decided for economical purposes, and for the fun of it, I'll be building my own exhaust. I'll be running three inch all the way back, and was hoping for suggestions from you guys for the cat and muffler combo. A friend that owned an FB had used magnaflow mufflers that were around 70$, and they sounded decent even on his 12a. With mine being a turbo though, are there any special considerations to be made? Do I need to worry about melting stuff on the cat or muffler? Do I need to buy "rotary" specific stuff?
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
If your going twins you can attempt the set up im thinking of unless your thinking of a budget custom exhaust build.
3' down pipe, with WB02 bung at the end.
3' high flow cat with air pipe inlet
Multi layer resonator welded into the midpipe
into 2 Apexi World Sport2 Mufflers to keep the noise down while retaining power across the board.
With this you can bring up your boost levels, and see some power gains. Also keeping the emissions active down stream. And with 3 levels of noise reduction from the cat/resonator/muffler you can retain your sleeper status. Be sure you have a FCD ready in place.
06-22-10, 02:14 PM
#15
MECP Certified Installer
I've decided for economical purposes, and for the fun of it, I'll be building my own exhaust. I'll be running three inch all the way back, and was hoping for suggestions from you guys for the cat and muffler combo. A friend that owned an FB had used magnaflow mufflers that were around 70$, and they sounded decent even on his 12a. With mine being a turbo though, are there any special considerations to be made? Do I need to worry about melting stuff on the cat or muffler? Do I need to buy "rotary" specific stuff?
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
I should also mention that I prefer nice, conservative exhaust notes. This build is sort of a "sleeper" you could say. And it needs to be emissions legal.
Linky...
http://www.summitracing.com/parts/MPE-10415/
There is a youtube video with an s4 and a few 12A's with those on, and they sound great. Nice thing is, since it is stainless, and has a wire mesh support, they won't blow out. Stainless tubing and outer shell as well.
On the same note, I do caution you that 3" may bit a bit too much. Mazdatrix recommend not exceeding 2.5 inches for even racing applications.
06-22-10, 03:22 PM
#16
Ok, so based on suggestions, I'll stick with 2.5".
I do plan on doing dual exhaust. However, I figured with the turbo, cat, and dual mufflers, I wouldn't need a resonator. (I suppose I can always add one later)
The Apexi mufflers, are they pricey? I'm not on a strict budget per-se, but I'd be happier spending less money
Gurew, I'm confused, how do more cats increase flow??
Does the air-pump inlet have to go "in" the cat? can it be in the pipe before the cat? I figured if I couldn't find a cat with an air pump inlet, I could weld the old one on the new one. Or are air inlets pretty common on most cats?
The RX7.com cat seems like it would work. It's a big chunk of change though, but I suppose it's the price to be paid to stay legal....
I do plan on doing dual exhaust. However, I figured with the turbo, cat, and dual mufflers, I wouldn't need a resonator. (I suppose I can always add one later)
The Apexi mufflers, are they pricey? I'm not on a strict budget per-se, but I'd be happier spending less money
Gurew, I'm confused, how do more cats increase flow??
Does the air-pump inlet have to go "in" the cat? can it be in the pipe before the cat? I figured if I couldn't find a cat with an air pump inlet, I could weld the old one on the new one. Or are air inlets pretty common on most cats?
The RX7.com cat seems like it would work. It's a big chunk of change though, but I suppose it's the price to be paid to stay legal....
06-22-10, 03:32 PM
#17
I'm pretty sure I want to stick with the magnaflow mufflers. But like I said, I REALLY don't want to be heard from miles away. Some people may enjoy that, I don't. I don't need to draw anymore attention from patrol cars than a bright red tuner car already does. And I just prefer/love the sound of a really conservative exhaust.
06-22-10, 06:31 PM
#19
The Firestarter
06-22-10, 08:51 PM
#20
You NEED to get a cat that has an air inlet pipe. This will help you pass emissions. It'll be hard as hell if you try to pass emissions without one.
You'll need a fuel cut defender. What this will do is trick the ECU into thinking that your boost won't go over stock (when it will creep up from your exhaust) whenever it goes over 8.8 psi I believe the motor will cut fuel to the rear rotor. Then pop goes the motor.
Another thing that is good to have is some sort of fuel controller also. With your wideband you can then tune it to a decent air/fuel ratio.
I have an FCD and an apexi SAFC neo for sale if you want either. PM me if you're interested.
Also post pics when you're done!
You'll need a fuel cut defender. What this will do is trick the ECU into thinking that your boost won't go over stock (when it will creep up from your exhaust) whenever it goes over 8.8 psi I believe the motor will cut fuel to the rear rotor. Then pop goes the motor.
Another thing that is good to have is some sort of fuel controller also. With your wideband you can then tune it to a decent air/fuel ratio.
I have an FCD and an apexi SAFC neo for sale if you want either. PM me if you're interested.
Also post pics when you're done!
06-23-10, 12:57 PM
#25
I hope you guys are ready for some crude drawings and odd questions. I'm trying to get my parts list together, and get an over-all cost drawn up.
Can I replace the red and green circled areas with one down-pipe? Or do I need to buy a pipe that will bolt to the turbo, then buy or build something that will replace the green pipe?
And how do I re-create the "y" pipe in yellow in 2.5", since I want dual exhaust?
Can I replace the red and green circled areas with one down-pipe? Or do I need to buy a pipe that will bolt to the turbo, then buy or build something that will replace the green pipe?
And how do I re-create the "y" pipe in yellow in 2.5", since I want dual exhaust?