Building A Custom True 3 Inch Exhaust in my garage
 

Gents, I decided to take the plunge and try to build my own custom exhaust system. However, I humbly ask for your guidance ... in return ... pics of my build.

But first, some background

BackGround:
There are two reasons behind this build.

Reason 1: Currently I have a racing beat midpipe followed up by a MS 2 canister catback. Although this set-up sounds great, it is less than ideal for performance. The flanges are 2.5 inch, the midpipe is 3 inch, and the catback is 2.5 inch.

Therefore, I want to build a true 3 inch header back exhaust all the way - 3 inch flanges - 3 inch piping.

Reason 2: I have very little welding experience (a bit of arc experience). However, my personal research and experience has led me to believe that if you want something done right, you either have to do it yourself or pay someone a lot of money (which I do not have). Eventually I want to build a completely custom low mount turbo system, and I want this build to be practice/learning to weld.

Owning the rx8 has been one huge learning experience. Three years ago, I barely knew how to do an oil change. By now, I am proud to say that I have either assited or have taken apart almost everything short of parts of the interior and the transmission itself. I think it is time for me to step up my game and enter the fab world.

What I am I thinking
- True 3 inch, single exit, possibly twin, but I have not decided
- One Spiral Style Resonator
- One Muffler
- Bolts up to stock header, 2 or 3 pieces (akin to stock)

Tools I need
- Welder - I know TIG is expensive, and I have been doing some research on it. I would really like your guys opinions in this area. Should I buy new? Used? Supplies I will need as well as running costs ... I am thinking 1 - 1.5k for this

- Pipe Cutter - same as above except for the price range. Where do I even find one?

- Pipe Bender? - I found some pre bent pipe kits online... see below for specific one I am looking at.

Parts I am looking at

- Piping: This (needs to be bent http://www.summitracing.com/parts/SUM-640030/)
OR http://www.summitracing.com/parts/FLO-15902/

- Resonator: http://www.summitracing.com/parts/MOR-94051/

- Muffler: http://www.summitracing.com/parts/SUP-546-3019/

- Header Flange: can you help me locate one?

- Midpipe Flanges:

Can I use ebay for flanges?

I plan on starting this in a month or so.

saved 4 pics ... which will come later .... but for now you can feast your eyes on this picture ... Kinda sums up how I feel about this situation ...


http://static.blol.me/photos/1273946176493.jpg

Very excited to see the results. I've been on the hunt for a true 3" off the shelf system, but obviously haven't found one :rofl: .

pics to come

Thanks man!

Yeah ... this is phase 1 for me. I will probably be selling it once I am done building it....

You do realize that just about EVERY after market is 3" right?

flanges aren't therefore you don't get the best flow characteristics

I would inquire to Charles @ BHR about the use of that Moroso resonator for rotary applications.

I would buy a used midpipe and use it for the flanges and the bent pipes...I did that with mine. I cut out the resonators that were in it and replaced them with the new ones...and welded it all together.

You can do a decent job on an exhaust with a MIG....not quite as pretty...but as functional and a lot less work than TIG

Attachment 289311

Get Some

oh shit. I fuxking spit on my screen. u asshole. u better pay for my monitor !

I seen that pic like 50 million times but ... damn u caught me again.

well seriously, do we need 3 inch piping at all?

Not for N.A ... 2.5 is perfect I think. BUUUT for FI ...

read some on exhaust therory. Burns is a good place to start
Applaud you increasing your skills--i haven't learned to weild either. Do it guy.
The hot side of the engine gets complicated with a turbo addition.
I would go with weight reduction--meaning single exhaust. I think I would place the resinator further back on the midpipe.
Learn how to also measure exhaust back pressure--you can defer much work chasing an idea by doing that. Concerntrate on exhaust gas velocity.
Tube headers--flame suit on---IMHO are not good for this engine. We have true zero overlap with the oem ports. A better designed log header would be the best---again imho.
You are dead on with it comes to the collector--that area can use a lot of help!

Clever approach with the Supertrapp, and having the ability to add more plates to the muffler to control the sound somewhat is an added benefit. Aestetically, not sure how it will look on an RX8, but should function well. I totally forgot about those mufflers! It's probably gonna be loud dude so load up on those plates. Burns repacks also would be a good option as dragger stated.

Thanks for the comments, guys.

OD, I have my own ideas about the header that I want to try out, but I do believe that I have cracked it.

I agree that without implementing these, a log header would be best. If I were to build one, mine would be a hybrid, but that is all I am willing to share at this point.

BB rx8, I will look into that stuff in more detail

find a way to make this work

Attachment 232717

lolololol

I can't even tell wtf that is ... a W rotor?

lol its a long tube header design by Defined Autoworks for a 20b

Attachment 232715

http://www.rx7club.com/showthread.php?t=940846

I think that header could use a few more loops and bends. It's too straight, bad for flow obviously.

interested in seeing how this goes.

me too ... I'll update when I acquire said welder.

What does rx8club have to say about this guy:

http://www.youtube.com/watch?feature...&v=SkcN8-JtknQ

not qualified to voice an opinion.
have you talked to burns yet? Call them --they can help figure out what pressure waves are happening and how to design the system---megaphone, stepped--whatever. I bet they dont have much experience with zero overlap engines--except a few flathead fords they have probably done.
Have you measure the exhaust system back pressure?
i have been meaning to do that--just havent had the chance.

bump on this thread.
It got me interested in exhaust system design.