Custom Exhaust

[bpestilence]

So, as one of many projects that I am working on whilst overhauling my car, I am putting together a new exhaust. Here is why:

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As you can see, the old 3" exhaust in the car isn't quite up to standard. Sure, it was doing its job, but it is ugly, and I am sure that the several unecessary bends, including crush bends, aren't helping out with engine output.

Firstly, I found that the muffler is a good one. Although very dirty and welded to mild steel pipe, the muffler itself is 304 stainless. So, to go along with the look of the car I powdercoated it black and reinstalled it. Ordinarily, I would start fabricating an exhaust from the turbo, working my way back to the back of the car. But, with no engine in the car right now, I went backwards, starting from the muffler and working my way forward.

Here are the pics:

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This shows the look of the newly powdercoated muffler. I just kept the hangers that were already on it. That made reinstallation easy and also gave me a good basis for the rest of the exhaust.

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Side view.

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Here I have welded the first bends to the muffler. These are really the only bends necessary for the exhaust, unlike the many smaller bends on the old exhaust.

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Then I hang the exhaust I have made back in the car, and start mocking up the straight section. The plan for the straight section is 2 10" long resonators, a high-flow cat, a flex coupler and a v-band. The v-band will then connect to the 2.5-3" downpipe I will finish later.

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You can see that I just hung the pipe up with some aluminum welding wire.

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The two resonators are now welded on.

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Can you tell which welds are mine and which are robotic? Of course you can.

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This is my favorite Christmas present. Makes making straight cuts easy. Cutting 304, though, I tend to go through a $10 blade every 6 or 7 cuts.

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Might be hard to see, but here is everything to date. The resonators, straight section, and cat are welded in. The length of straight pipe places the cat under the stock heat shield.

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And here are a few pics of the exhaust reinstalled. As you can see, it fits fine, with the suspension fully relaxed, and without having to make a bunch of bends. Should flow pretty well.

Later: When the engine is installed the downpipe fabrication, v-band, and flex will follow!

 

[Dsmj89]

Looks good man, great job and clean work.

 

[SuzukiRidr326]

looks awesome man..great job!

 

[awdrst]

Looks good. About going through the blades so fast. Spend the money and get a nice one from a place like McMaster Carr they cost about $40. I use the same saw and cut everything from sch10 304 pipe to 18 gauge ss tube for exhausts and I go through a blade about every 6 or 7months and I cut ALOT of steel. Also making a nice base for those saws is a must do. The sheet metal ones they give you are scary at best. With some cheap box tubing and a welder you can have a real nice stand.

 

[bpestilence]

Now that the engine is back in the car, I have been working on the high-flow downpipe. Here it is!

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Step one, place the flange on the turbo and check out my options. We all know that there is not a lot of space here to have a full bend without hitting the alternator. Cutting a bend down without changing the angle is the best option, but the more you cut the more oval the pipe becomes.

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For a happy medium I went pretty much halfway between a full bend and the cut that you would have to do to bolt up to the stock exhaust. I am not so constrained. The downpipe also angles a bit forward to give a better sweep.

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In the car the bend seems to give plenty of room. I will put soem heat shielding on the alternator to be safe.

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Here I weld on the reducer and the second bend. This enlarges the 2.5" downpipe to 3" to meet the rest of the exhaust, and does so smoothly with a gentle bend. Using a transition like this is actually superior to just making a 3" downpipe because of the rapid transition that would have to occur from the outlet to the downpipe.

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Final bend. About 20 degrees of pipe here just to make the exhaust level with the ground and angle the exit directly back at the rest of the exhaust. With the bends in place this downpipe looks a bit like a musical instrument.

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Back in the car with the full downpipe mockup. Now to finish it!

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Using some really thin steel, I mockup the wastegate pipe, and then once satisfied, cut out a copy out of 16ga. I am aiming for a "y" entry here, considered by most to be the ideal entry for a wastegate tube. I am also entering at the transition so that the CSA of the downpipe doesn't change much overall (with the WG open).

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A Dremel with a fiber-reinforced cuttoff wheel makes short work of the entry port. I have also welded on the accessory bungs at this point. Stock O2, WBO2, and EGT.

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Almost done. But wouldn't you know it, I ran out of Argon and the TIG went to insta-slag mode. So I have some cleaning up to do and this hole to close up.

 

[alansupra94]

That 2nd tube is for the wastegate dump right?

BTW those pipe cutters are amazing, straight all the time! I used them on a Subaru''s exhaust before.

 

[spooln4fun]

Very nice work there, been wanting to do the same thing to mine, just never made time yet! get us a sound clip when your finished!

 

[SuzukiRidr326]

that look amazing man...looks like its fun too!

 

[bpestilence]

First problem with the installation. Angling the downpipe forward was a great idea for alternator clearance however I ate up some intercooler pipe clearance. So I have to put a little more work into the IC pipes.

BTW, I really suck at welding aluminum. Just throwing that out there. My new aluminum IC pipes look like I welded them together with bird poo. Nothing a lot of filing, extra filling, and a liberal powdercoat won't fix, though. Just don't try to stand on them.

 

[alansupra94]

First problem with the installation. Angling the downpipe forward was a great idea for alternator clearance however I ate up some intercooler pipe clearance. So I have to put a little more work into the IC pipes.

BTW, I really suck at welding aluminum. Just throwing that out there. My new aluminum IC pipes look like I welded them together with bird poo. Nothing a lot of filing, extra filling, and a liberal powdercoat won't fix, though. Just don't try to stand on them.

I got a professional welder that does all my work. I might try and learn to weld but I am swamped with school work and my mom already gets pissed when I work on the car. I can't imagine what she would do if I started welding things

 

[kenamond]

Custom fabrication on your DSM...in Hawaii. I'm jealous.

 

[bpestilence]

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Final install on the downpipe.

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Just for fun, here are the new aluminum IC pipes. I am not going to show much process here. This is the pipe from the J-pipe to the intercooler. Most complex piece.

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The 180° pipe here was my first and worst weld. Remember how I said my welds were turning into bird poo? Well, this is embarassing to say, but I actually had the machine set wrong. All this time I didn't know there was an AC/DC button on the welder! I thought changing the frequency did that for me. Oops. Now my welds are better. Still not professional, but I got a couple stacked coin beads (and then blew through and made 'em ugly again by filling in)

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The other side of the intercooler...

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Up through the SMIC hole and the SQV BOV...

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Then to the TB. The last piece is steel (leftover from my old charge pipes) Because I needed to weld in one last steel bung.

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Here it is. Bung for the water/meth injection.

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Overall look. Hope you enjoy.

 

[awdrst]

When welding aluminum there is no such thing as to clean. I make sure they are as clean as possible before welding. It will make a huge difference. Also what machine are you using and what settings are you at when welding the ic pipes? Aluminum is a tricky at the start since it takes a bit to get up to melting temp and than just gets hot quick after that. Post up some close pics of your welds maybe we can help you out with getting better quicker.

 

[awdrst]

Also is the steel you are using for you exhaust mild or stainless?

 

[bpestilence]

Still waiting on the damned flex joint. Got shipped to the wrong address now I have to wait on another one. The guy who said he was jealous of me fabricating things in Hawaii? Don't be. At least you can go to a speed shop or something if you need a part. There isn't any decent speed shops on island, no AWD dynos, no race tracks, and the local SCCA autocross "track" is a joke. can't wait to get back to the mainland.

Besides that little setback, the car is almost ready to go. I could fire the engine now but it would be loud with no exhaust on it. After that I just need to put the suspension back together, replace the tranny and diff fluid, and drive. After the engine is broken in, in goes the F/IC and 750cc/min injectors, and up goes the boost.

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[kenamond]

Still waiting on the damned flex joint. Got shipped to the wrong address now I have to wait on another one. The guy who said he was jealous of me fabricating things in Hawaii? Don't be. At least you can go to a speed shop or something if you need a part. There isn't any decent speed shops on island, no AWD dynos, no race tracks, and the local SCCA autocross "track" is a joke. can't wait to get back to the mainland.

There aren't any dynos, shops, etc. near enough for me to take advantage. I either do it myself or don't do it. I recently found a great local weld-guru, though, so not having the welder or skill to use it isn't a problem.

Are you concerned at all about the endtank design of that FMIC? Looks like you'll only really use half the core. The water/meth injection will help, though.

 

[bpestilence]

Yes, but not so much that I am going to buy a new one or cut it apart. Intercooler came with the car.

There weren't many shops near Seattle, either, but I have driven across three states to get a car tuned before. Not even an option here.

 

[kenamond]

Yes, but not so much that I am going to buy a new one or cut it apart. Intercooler came with the car.

There weren't many shops near Seattle, either, but I have driven across three states to get a car tuned before. Not even an option here.

Looks like you might have enough room to make longer, more "triangular" endtanks with inlet/outlet more centered. Then you can practice your Al welding some more.

 

[Imback]

Over all not to bad. Why aren't you just tig welding all the pipes? Also what wire and gas are you using on the stainless? If you fitted the pipes a little better the bead it's self would of came out better.

 

[bpestilence]

Okay enough. No more welding advice from people who didn't even bother to read the post. Just to clarify,
1) I know that you need to clean aluminum to weld it. It wouldn't weld at all if it were dirty. If you would have actually READ the thread, you would have read that I had the machine set wrong at first.
2) It is TIG. All the joints are either lap welds or butt-welded using a vertical bandsaw for fitment (again, in the thread). If you think you can weld better, go ahead. Then post a threat about it so I can make inane comments without reading it.

Final installation! Finally got the flex piece so the exhaust gets complete.

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The complete downpipe. Should flow pretty well. I am hoping the design makes the 16G want to creep a little less.

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The final bit of the exhaust. Getting this V-band to fit together was a b**ch.

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Overall look.

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And, after finally getting that V-band tightened down. Whew. I think I am done fabricating for now. Moving onto the suspension rebuild. I will get a sound clip later.

 

[Imback]

Ok i read the thread and i don't see what your trying to point out to me? And if those are all tig welds you should honestly go to a local college for a refresher course they look to me like a mig weld with the in proper gas. 1 proper pass with tig is more then enough for any exhaust system. If you did not want people to judge your work then don't post it in the fabrication section of the site. I do this for a living and am giving you my honest opinion if you don't like it then.. It is what it is.

 

[Imback]

These are just little 5 minute projects i did at the end of the day.

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[Burnett03]

Not bad.. Do yourself a favor and tie up that driveshaft with a coathanger before you damage it.

 

[bpestilence]

Congrats. You can weld. You are a god among men and your penis is bigger than mine. Now if you feel satisfied, please go make your own threads and stop hijacking mine.

Just to "help me out", though, why don't you tell me where this looks like a MIG weld:

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Notice that my weld is the same color as the robotic welds. It is the material, not the welding. 304 steel doesn't make pretty rainbows like 316 does. Dang.


The driveshaft is connected. It was not connected for the first couple shots.

 

[Burnett03]

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The driveshaft is connected. It was not connected for the first couple shots.

What i'm saying is never leave it hanging at that angle.