3" Downpipe build [Archive] - SaabCentral Forums

: 3" Downpipe build


coosabrew
15th November 2013, 10:01 PM
Has anyone here made their own downpipe on an SS? Looks fairly simple, just lots of welding. Maybe a couple of 90*'s and a couple straight pieces. If so, looking for tips or pics would be great.

Squaab99t
2nd December 2013, 02:09 AM
Has anyone here made their own downpipe on an SS? Looks fairly simple, just lots of welding. Maybe a couple of 90*'s and a couple straight pieces. If so, looking for tips or pics would be great.

Looks simple, but if you do it right in the correct materials it is an involved project. I worked on mine for 9-3 2.0l for the past 3 months off and on. Finally finished today, except for the O2 bungs.

http://farm4.staticflickr.com/3797/11167020605_f589d0dbbb_z.jpg
1) I decided to keep my car with a cat, but go with a better flowing Magnaflow and a nice smooth bend coming off the turbo in 3".
2) Yes a lot of skilled welding, and: Machining, fitting, tooling, planning, and part sourcing.
http://farm8.staticflickr.com/7320/11167087344_8734003481_z.jpg
3) Using an OEM DP as the authority, I built tooling to insure good fit up on install. Also as a fit check as I welded. If you weld too much in one area at one time, it will warp the part.
http://farm3.staticflickr.com/2845/11167058486_1aa784bf4b_z.jpg
4) Back purging with argon is a must to keep the corrosion properties on the welds inside the tubes. Plus the inside looks as good as the outside. The exhaust gases will enjoy the view as they fly by.
http://farm4.staticflickr.com/3788/11167250456_09c50889c4_z.jpg
Here is a photo album:
http://www.flickr.com/photos/[email protected]/sets/72157638271877156/

swedespeed7
2nd December 2013, 10:59 AM
Beautiful welds, and nice to see proper equipment in use!

DeckManDubs
2nd December 2013, 11:26 AM
Well done ;ol;

rabbit
2nd December 2013, 11:36 AM
The work on the downpipe looks really nice. But why did you bother to keep a stock cat? I would highly recommended a 3" racecat to replace it. You might just be limiting the potential this could have for making good power safely with that stock cat.....

swedespeed7
2nd December 2013, 11:37 AM
The work on the downpipe looks really nice. But why did you bother to keep a stock cat? I would highly recommended a 3" racecat to replace it. You might just be limiting the potential this could have for making good power safely with that stock cat.....

He used a race cat, seen in first pic. The pic with the stock cat is just showing how he mocked up the shape.

9-3gotboostAERO
2nd December 2013, 11:39 AM
So squaab when are you going to start mass producing these? lol

Squaab99t
2nd December 2013, 02:27 PM
So squaab when are you going to start mass producing these? lol

Thanks folks for the reviews.
The first one is always the toughest to build. Double checking, second guessing your setup and your first few cuts.
I've always built resale components for the 99s and 900c, but the population of those are dropping. Maybe it is time to revise my product line?

coosabrew
2nd December 2013, 10:08 PM
That is very nice. Decided to buy one from Genuine Saab. Holidays and stuff makes for loss of time. You got my juices flowing tho! I like the idea of the build to the OE, then flange 3" to the rest. Makes it easier to go back to stock, if needed.

SYQ SAAB
3rd December 2013, 12:21 AM
That looks really good and I like that it's two pieces and that you used a CAT. That way you don't have to change it out. If you decide to make more I might buy one depending on the price. since I don't really GS stuff.

Squaab99t
3rd December 2013, 08:48 PM
That looks really good and I like that it's two pieces and that you used a CAT. That way you don't have to change it out. If you decide to make more I might buy one depending on the price. since I don't really GS stuff.
Well right now it is a prototype for myself. The plan was to make it plug and play to keep the ECU happy and no additional "custom" parts or mods to get it to work with the rest of the exhaust system.
I'll add up the cost of materials, sub contracting the flanges on a water jet/lathe, and my time to come up with a price. Then gauge the interests. Being up front, this not a budget 300 usd downpipe.
Thanks for the feedback.

Squaab99t
3rd December 2013, 09:00 PM
That is very nice. Decided to buy one from Genuine Saab. Holidays and stuff makes for loss of time. You got my juices flowing tho! I like the idea of the build to the OE, then flange 3" to the rest. Makes it easier to go back to stock, if needed.
I've been in the same position. Sometimes it is easier and better to buy something commercially off the shelf. In this case, I had not built a downpipe yet so, it was a learning experience and exercise in fabrication.

Squaab99t
4th December 2013, 05:42 PM
Better pictures with a proper camera and conditions.
http://farm8.staticflickr.com/7353/11211371773_c73448afad_h.jpg
http://farm8.staticflickr.com/7441/11211244265_9b4d7094d9_h.jpg
http://farm4.staticflickr.com/3820/11211236855_888171d47c_b.jpg
http://farm4.staticflickr.com/3777/11211238056_0438a26f04_h.jpg

Squaab99t
13th December 2013, 09:42 PM
I added pre and post cat O2 bungs like the OEM locations. I decided to try a saddle style to do a couple things. With the saddle it spreads the load out and lowers the chance of the bung breaking at the base. Really not a problem with .063 tubing, but I have some 20 ga .035 wall on one leg. IMO it is also easier to do a lap joint than a fillet.
I found these stainless castings from Vibrant
http://farm6.staticflickr.com/5508/11360847353_a5ee4e2ff4_z.jpg
Burnsstainless makes hog outs at 3 times the cost. Very nice but $30 per.
http://www.burnsstainless.com/images/products/display/O2SR.jpg

They welded up pretty nice. I used 1/16" 309L filler rod to prevent any chance of blow thru on the tubing. With that thick of rod you can freeze the puddle and have good control, but it is a little lumpy. Still had good penetration by evidence of the internal shots.
http://farm3.staticflickr.com/2881/11360752926_513c758453_c.jpg
http://farm8.staticflickr.com/7372/11360785854_80bf3d36ff_c.jpg
Used a wadded up aluminum foil to plug the bung while it was back purged. It is cheap and no worries about the O2 plug welding it self into the O2 bung threads.
http://farm3.staticflickr.com/2873/11360894375_5f6dcbfa6c_c.jpg
http://farm4.staticflickr.com/3749/11360753386_4b97825912_c.jpg
Now need to find the time to pull the old and put in the new. Also need to order some ARP fasteners since the OEM used studs in the lower flange.