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View Full Version : Looking for dimensions for making custom exhaust parts (test pipe/downpipe)



Nevalite
07-22-2012, 04:34 PM
Hello Everyone,

I am thinking of making myself a test pipe like the 034 motorsport one and a new down pipe to connect the test pipe to the rest of the exhaust including the flex tube. I have access to a full machine shop along with all welding equipment. I have experience on the lathe and the mill, not as much with welding but I am looking at making this project a learning experience for me. I will be practicing my welding before doing the actual welds on these parts.

I am just wondering if anyone has done such a project or if the dimensions are given anywhere? I am thinking of using 304 stainless steel, probably 2.5" or 3" not sure yet.

I am going to model the part in solid works ahead of time if anyone has any CAD models of that area of the car.

Any info or tips related to this project would be appreciated.

Thanks

Matt

Seerlah
07-22-2012, 05:01 PM
Take the cat and downpipe out of the car, bolt it back together, and construct a jig for it. Then use that jig to make your custom parts. And when I had my custom downpipe made, it was made with a u-bend peice of pipe. He simply cut, fit, and welded it for perfect fitment. Came out really well.

Nevalite
07-22-2012, 05:10 PM
Could you elaborate on the "construct a jig" part, sounds like a good idea I just don't know what that is :)

thenj3
07-22-2012, 05:21 PM
then idk if your up to building an exhaust lol. just buy my 034 test pipe and neuspeed cat back thats in the classifieds

Nevalite
07-22-2012, 05:24 PM
I understand that it's set up to hold your parts in place while welding I was wondering how he set it up to get the bends right etc...

Seerlah
07-22-2012, 05:30 PM
I have never done this myself before, but this is how you would want to do it. You make the jig so you can make the bends, length, curves, angles, etc correct. The jig is not just used for holding parts in place while welding. And really, marking the 2 sides of the parts you want to weld and doing it on an actual bench would seem a better route to me. Then bring it back to the jig, and see if it sits properly. But it sounds more like you want a mandrel bent system, and not a cut and welded one. Use the jig to test fitment issues. Use it for your trial and errors.

Well, this was just one way to go about it. There are others.

Poopie
07-22-2012, 09:31 PM
This is what i would do

-take the cat off
-get the measurements you need to cut the two flanges for the cat section
-cut out TWO of each flange
-bolt one set of flanges to the cat
-use some scrap metal to weld the flanges to a base in a fashion so that the two cut flanges will not move in relation to each other. You should be able to bolt and unbolt the cat and the faces of the flanges will meet up perfectly. This is your jig. You now have a flange that will act as the turbo placement, and one flange that will act as the flange on the downpipe.
-Bolt the SECOND set of flanges to the welded up pieces.
-guess on your bends and obstructions
-tack in the tubing to the flanges that that bolted to the jig flanges. two spots will do.
-unbolt the mocked up test pipe and bolt it to the car and check for fit.
-make any changes if necessary, if not, finish weld the part

after all that work you will wish you just bought one. but if you cut out a bunch of flanges, you can use you jig to make up a bunch of test pipes and if you sell them for under $100 a bunch of people will buy them.

Nevalite
07-22-2012, 11:53 PM
This is what i would do

-take the cat off
-get the measurements you need to cut the two flanges for the cat section
-cut out TWO of each flange
-bolt one set of flanges to the cat
-use some scrap metal to weld the flanges to a base in a fashion so that the two cut flanges will not move in relation to each other. You should be able to bolt and unbolt the cat and the faces of the flanges will meet up perfectly. This is your jig. You now have a flange that will act as the turbo placement, and one flange that will act as the flange on the downpipe.
-Bolt the SECOND set of flanges to the welded up pieces.
-guess on your bends and obstructions
-tack in the tubing to the flanges that that bolted to the jig flanges. two spots will do.
-unbolt the mocked up test pipe and bolt it to the car and check for fit.
-make any changes if necessary, if not, finish weld the part

after all that work you will wish you just bought one. but if you cut out a bunch of flanges, you can use you jig to make up a bunch of test pipes and if you sell them for under $100 a bunch of people will buy them.

Thank you very much for this advice, I will definitely do something like this.