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Documenting custom 3" Exaust work

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documenting custom 3 exaust work
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6.5K views 55 replies 16 participants last post by  SleeperWagon  
S
#1 ·
So, when my friends and I get back from the beach, (Sunday) we're going to start fabbing my 3" custom catback exhaust. Should I take pics as we go along? Bought 16' of aluminized 3" pipe for $75 from Jegs, an identical Borla muffler to the one in the $1000 TT stainless 2.5" setup (but in 3"), and a 22" Cherry Bomb glasspack. Hoping for it to sound pretty good. It's going on my Frankenturbo'd (F4H) AWM 1.8T.

We just bought a 3" pipe bender from good ol' Harbor Freight, and we can weld aluminized pipe no problem. Anyone have any pointers or tips for us to watch out for on this project? Just looking to feel all of this out. Thanks guys!

(And yes, I'm back :p )
 
#9 ·
or fill it full of water and freeze if it's a manageable length. works like a charm
 
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S
#10 ·
Hmm, that's not a bad idea, only problem is that each section of pipe is 4 feet long. May try to cut it and throw a piece in the freezer... but that's also time consuming. Thanks for the insight though :)

Just got back from Ocean City an hour ago with the bros, going to assemble the bender tonight. Taking the exhaust off tomorrow or Sunday.
 
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#11 ·
Well, started tonight, took the exhaust off and saw what happens when you bend big pipe without stuffing it full of sand as a test. :lol:

Full stock exhaust
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Open downpipe...
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This is the bender... maxes out at 3" lol
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Sleeve-back exhaust with suitcase coming down (So glad to finally get rid of that piece of lead)
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LOL, yeah, I think we're gonna need some sand and caps. (2.5" pipe section)
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So that about sums up the first night. Didn't want to get to into it because we started late... starting back up tomorrow with bending/welding/cutting earlier.

Oh yeah... this project is gonna be a BITCH.
To future custom exhaust fabbers, if you don't have to run a 3" exhaust because you're running a huge turbo, DON'T. It's much easier to run 2.5". I don't even know if theres enough space for the 3" pipe to pass through the body from the bottom of the downpipe. We'll see :crazy:
 
S
#14 ·
Fuck. This bender will NOT work for this 1/16th inch thick steel 3" pipe. This is what happens when packed with sand TIGHTLY to the brim. Anyone wanna buy a pipe bender? lol

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I was afraid of this... Any other suggestions? We filled a new section up with water and sealed one end and threw it in the freezer... I hope the ice method will work better than the sand method. The sand we have may also not be fine enough... But we even tried sifting out the rocks that were in the sand to get it very fine. We even used concrete mix which is just like a powder, but of course that had rocks in it as well that we attempted to strain out. Why the fuck is bending a few pipes so difficult?

And one for the road... Cutting the flange off the mid pipe to weld it to the new pipe, then we will bore the flange out to about 2.75".
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We're probably going to end up resorting to cutting lemon slices, if you will, out of the pipe and weld them all together to make a bend. Time consuming, yes, sloppy, yes, but it'll get the job done.

(Being inexperienced sucks)
 
#23 ·
Well, it looks like the frozen trick was a success, yes? This techinique is used when making musical instruments like french horns, trumpets and trombones. The brass used is so soft that it would kink when being bent if it wasn't filled with ice.
 
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#26 ·
Frozen pipes (2 of 4 that were in there)
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Bent pipe, didn't even have to cap the ends
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Bent, and welded. Stock bored out flange on one side, 3" flange on the other. Will explain the significance of the small diameter pipe if needed.
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So far, we've gotten it down to the middle of the car where the glasspack ends. It's really actually coming along nicely, but I don't want to jinx it.
 
D
#29 ·
Are you using a 220 volt or a 110 volt MIG..??

I have fond memories of my dad repairing his old work van to keep it on the road. Ended up burning more holes in the sheet metalwork than actual useful welds whilst he was learning. Didn't help that he was using wire that was too thick.

Learning on heavier metal is easier than trying to learn on thin sheet steel.
 
T
#30 ·
'True' Mandrel bending takes a lot more than just a big bender and some packing material, which is why the few places that do it charge out the nose for it. That's a neat trick with the ice, though. (Water'd work even better if you could seal the ends against the pressure.) I work in the industry and everyone I talk to says sand is the preferred method. Even if it hadn't worked, if you could have 'minimized' the crumpling on the elbow, a press-bent corner on a 3" pipe would still be pretty impressive. But I'd pre-buy mandrel bends before slicing things up for SURE...

Newman, it's bragging rights for sure. But still, I read an article where some guys disproved that theory. They mounted progressively larger exhausts on a small turbo system and saw gains up through 4" pipe! So even though you can get similar performance from smaller pipe sizes (with more mods to do so) there still must be some restriction...
 
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