Switching it up a bit, I built something for the new ride. I applied what I learned from when I helped my friend Kevin build his dyno headers for his big block Chevy. Needless to say this was a lot less welding.
All the techniques are applicable to any exhaust component for any car.
Utilizing a OEM downpipe/cat I built a weldment jig to help make it plug and play into the car.
Making use of an inherited strongback, I add some features to locates the flanges
The plan was to keep the turbo interface and the mid pipe interface in the same place and stay within the envelope of the OEM.
Genuine Saab had the turbo flange so I used his, but had to machine the lower flange.
Lots of fitting to find the sweetspot and piece by piece tacking.
Argon back purge the inside of the tubing for nice clean welds and this keep the corrosion and strength proprieties of the stainless. The little black blob was from the tack in open air.
Welding thin wall .063 to .375 flanges take a lot of practice to control the arc and the heat. It is challenging to get a nice puddle on the flange and the tube without blowing a hole in the tubing. I used .035 308L filler rod. Also stitch weld,(1-2 inches) jumping back and forth across the tube. Don't be tempted to start in one place weld all the way around in one continuous pass.
Final tack while back in the jig. The elbows slip into the cat, so this leaves some fudge factor to get it dialed in if the parts twisted, warped, grew, or shrunk during the other full welds.
You can also see the cardboard and outline of the OEM cat in the background. A little bit outside the box, but I think I'll be good.
Money shots:
Still need to add the first and second O2 bungs. Then the moment of truth, does it fit?
9-3 SS 2.0l Downpipe fab
Re: 9-3 SS 2.0l Downpipe fab
Awesome work Dennis! Nice to see your strongback jig- that thing made all the difference between a part that should fit and a part that WILL fit... I'm confident it'll just slide right in there!
So for clarification, the bulbous thing in the middle of the pipe is an aftermarket mini cat?
So for clarification, the bulbous thing in the middle of the pipe is an aftermarket mini cat?
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- Crazyswede
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Re: 9-3 SS 2.0l Downpipe fab
Could be a cat. As I recall the 9-3 has a cat in the down pipe and another one under the car.
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Re: 9-3 SS 2.0l Downpipe fab
Looks like Magnaflow's spun stainless race cat, I've put those on a few cars, they work pretty darn well and you can see right through them. They have corrugated metal webbing that the catalyst is bonded to rather than ceramic, they seem to hold up well.
That looks awesome.
That looks awesome.
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Re: 9-3 SS 2.0l Downpipe fab
Mezzanine wrote:Awesome work Dennis! Nice to see your strongback jig- that thing made all the difference between a part that should fit and a part that WILL fit... I'm confident it'll just slide right in there!
So for clarification, the bulbous thing in the middle of the pipe is an aftermarket mini cat?
The strongback is a nice way to be sure you are doing your best to get it to fit the OEM arrangement. It one were to ever make another it would make it that much easier, if the first one works out...
Good eyes, Magnaflow spun cat. Yep, this 9-3 and most other modern cars have that cat very close to the exhaust manifold. I wish I could tell you it is some fluid dynamics, expansion, transonic, scavenging, power making, flux capacitor, but it is just a cat to keep the ECU and wife happy.
I'm pretty happy with this type of cat. Low profile, good construction, and seems to flow well. I am using one currently on the 900c.
- squaab99t
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Added Pre and Post O2 bungs
Final additions:
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
Burnsstainless makes hog outs at 3 times the cost. Very nice but $30 per.
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 shot.
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.
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
Burnsstainless makes hog outs at 3 times the cost. Very nice but $30 per.
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 shot.
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.
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Re: 9-3 SS 2.0l Downpipe fab
that's some nice welding you have done there!
Good work.
Good work.
- squaab99t
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Re: 9-3 SS 2.0l Downpipe fab
gert-jan 44 wrote:that's some nice welding you have done there!
Good work.
Thanks for the complement. It has been a fun project, but now it's time to see if it fits.
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