Miata downpipe T3 with external gate.
 

After buying a downpipe from a company and having it not come even close to fitting I decided to build my own. This was my welding project pretty much ever except some light practice the day before I started. I taught myself to Tig weld as well as how to weld stainless just for this project.
Mild steel flanges and all tubing is from Racing solutions. O2 bungs, flex section, and stainless transition is from verocious.

I installed 3 O2 bungs. One closer to the turbo for the stock narrowband just to keep CEL's away. Two in the rear, one on top for the wideband and one on bottom for the dyno. It transitions from 2.25" tubing off the turbo to 3" with the WG dumping back into the downpipe after the transition.
My welding wasn't the best by any means and I didn't have the setup to backpurge everything but it came out well and should work great.

https://lh3.ggpht.com/cjernigan/SCZQ...JPG?imgmax=800
https://lh5.ggpht.com/cjernigan/SCZQ...JPG?imgmax=576
https://lh5.ggpht.com/cjernigan/SCZQ...JPG?imgmax=720
http://lh6.ggpht.com/cjernigan/SCZQt...JPG?imgmax=512
http://lh6.ggpht.com/cjernigan/SCZQr...JPG?imgmax=512

Re: Miata downpipe T3 with external gate.
 

lookin good. Where the pipes meet the flanges, are those only partially welded because you welded the inside all the way around too?

Re: Miata downpipe T3 with external gate.
 

Yeah I welded the inside of the flanges completely and stiched the outside to help with thermal expansion and cracking. I've had alot of people tell me that when you weld the entire outside they tend to crack at the miniscus of the weld. I did this with both the turbine and outlet flange. I did not do this with the wastegate tube though and I hope I don't have issues now because of that.

Re: Miata downpipe T3 with external gate.
 

perdy clean. better than my oxy welds. ill be posting those soon.

Re: Miata downpipe T3 with external gate.
 

Looks good, I need to learn to weld.....

Re: Miata downpipe T3 with external gate.
 

Back the heat down and make 4 more and youll be selling them like hotrex.

Re: Miata downpipe T3 with external gate.
 

I think you could do alot better if your worked on your fit up.

Re: Miata downpipe T3 with external gate.
 

THe fitment is fine, he just didn't have the right size bolts and coat hangers for filler.

Re: Miata downpipe T3 with external gate.
 

i dont know about that wastegate dump placement. might crack down the line.