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View Full Version : built a custom 2.5" mandrel bent exhaust in my friend's driveway today



Kyle H
01-13-2010, 11:47 PM
I finally got a 2.5" mandrel bent exhaust on my car....

The materials:
2 mandrel u-bends
3 exhaust hangers
1 6" flex pipe
8ft straight pipe
2 2.5" 3 bolt flanges
[already had the Techtonics Tuning HFC]
Total Cost (not including cat): $130
(plus a 3" exhaust tip left over from jerds exhaust)

Originally the plan was to make a new downpipe off of the cat, and then the rest of the exhaust after a flex pipe and another flange to take it off in 3 pieces from the turbo back. We decided Audi was stupid in making the cat/downpipe connection in the hardest spot to reach (which, according to jerd, is why audi mechanics get paid so much)... so we chopped the flange off of my month old cat and welded up a real one piece cat/downpipe, moving the flange down to a reasonable level.
http://khphotography3.smugmug.com/photos/764411116_JLSFV-L.jpg
After the downpipe there is a 6" flex pipe, then a 4ft straight pipe... and then jerd worked his magic in the rear end and routed the exhaust around the rear diff and out the back, which let us center it perfectly.
http://khphotography3.smugmug.com/photos/764410877_xUdpa-XL.jpg
When I had the turndown off of my stock 2.25" downpipe, I measured 95dB under load in the driver seat. Now I'm getting 88dB under the same conditions. (on an iPhone SPL meter, not accurate but it's consistent)

The car has less of a boost spike around 3k now, but if feels like it has more power throughout the rpm range. THANKS JERD!

beemercer
01-14-2010, 12:04 AM
Nice work, I like the DIY spirit. And in that spirit, tell me about your welder. I wanna pick one up to do work like this so I'm trying to get recommendations.

Kyle H
01-14-2010, 12:07 AM
That's my friends welder... It's a Hobart 140. He loves it, I don't know much about it. I've heard great things from everybody he talks to about it though.
http://i290.photobucket.com/albums/ll278/Volvosporter/DSC00644.jpg?t=1255830595
http://i290.photobucket.com/albums/ll278/Volvosporter/DSC00643.jpg?t=1255830689

beemercer
01-14-2010, 12:10 AM
That's my friends welder... It's a Hobart 140. He loves it, I don't know much about it. I've heard great things from everybody he talks to about it though.


Nice, thank you [up]

BlackLock_A4
01-14-2010, 12:42 AM
haha. Wow! Great job! [up][up]

It has got to boost your ego when someone asks you what kind of exhaust you have.
Response: "Custom, I made it."
[:D]

codymack43
01-14-2010, 06:15 AM
what kind of gains might this give you? Sound clips would be great!

Seerlah
01-14-2010, 06:53 AM
That system looks loud! Any plans on quieting it down, or you like louder exhausts? Can't beat $130. You really can, but it's just a figure of speech.

EuroDriven
01-14-2010, 06:56 AM
Nice work, I like the DIY spirit. And in that spirit, tell me about your welder. I wanna pick one up to do work like this so I'm trying to get recommendations.

FYI I have a chicago electric flux cored welder from harbor freight and it works wonderfully. I have never had an issue with the unit I have. You are unable to connect shielding gas, but I am very good at tig and mig welding and if you know how to weld the flux cored will work awesome. I have welded competition robots with it and have only ever broken 1 weld. I can stand on all my welds (1/2 square steel tubing) and they hold up, on top of that I am about 240 with clothes and shoes.

The welder I am referring to is only about 150$ at harber freight. For something like an exhaust and not structural applications it would work fine.

Although if you have the money you can get a half tank, the hobart 140, and a cart for both for about 800$ total and you will never need anything else, and you should be able to do decent mig welds on aluminum.

BTW I have had harbor freights auto darkening helmet for about 6 years, it still works and I have never had an issue with that either, the black out time on it it very low, and you wont get a flash. (Black out time being time it takes for the darkening to kick in)

beemercer
01-14-2010, 07:05 AM
FYI I have a chicago electric flux cored welder from harbor freight and it works wonderfully. I have never had an issue with the unit I have. You are unable to connect shielding gas, but I am very good at tig and mig welding and if you know how to weld the flux cored will work awesome. I have welded competition robots with it and have only ever broken 1 weld. I can stand on all my welds (1/2 square steel tubing) and they hold up, on top of that I am about 240 with clothes and shoes.

The welder I am referring to is only about 150$ at harber freight. For something like an exhaust and not structural applications it would work fine.

Although if you have the money you can get a half tank, the hobart 140, and a cart for both for about 800$ total and you will never need anything else, and you should be able to do decent mig welds on aluminum.

BTW I have had harbor freights auto darkening helmet for about 6 years, it still works and I have never had an issue with that either, the black out time on it it very low, and you wont get a flash. (Black out time being time it takes for the darkening to kick in)

Wow, thank you very much for the advice [up]

biketsai
01-14-2010, 07:08 AM
That system looks loud! Any plans on quieting it down, or you like louder exhausts? Can't beat $130. You really can, but it's just a figure of speech.

Well he does have a cat [:p]

Coopa
01-14-2010, 07:48 AM
Sounds clips asap?! [:D]
Looks really good. Soon as it warms up I'm going to have to fix my Iowa-salt-rusted exhaust. Airplane sounds [headbang]

Kyle H
01-14-2010, 12:09 PM
haha. Wow! Great job! [up][up]

It has got to boost your ego when someone asks you what kind of exhaust you have.
Response: "Custom, I made it."
[:D]
hahah, thanks man. I take pride in doing everything on my car myself (or with the help of friends)... It is pretty fun telling people what I've done to my car with limited resources and watching their faces go [o_o]


what kind of gains might this give you? Sound clips would be great!
Not sure... I plan on hopping on a dyno at the end of this month or start of next month. I've never seen any k03 guys do a downpipe like mine, so I'm thinking it will flow a little more than most off the shelf systems.


That system looks loud! Any plans on quieting it down, or you like louder exhausts? Can't beat $130. You really can, but it's just a figure of speech.
97dB max during the video (uploading now) at 35ft. I think california's limit is something like 95dB at 50 ft, and the SCCA limit is 93dB @ 50ft, so I may need a muffler at some point. I love the sound though.


Well he does have a cat [:p]
That counts as a muffler, right?! [>_<]

pics:
http://khphotography3.smugmug.com/photos/764692378_RBN39-L.jpg
http://khphotography3.smugmug.com/photos/764693655_CZTDF-L.jpg

video is uploading.... 30mins remaining right now.

VMRWheels
01-14-2010, 12:19 PM
Wow, nice job! I've always wanted to do some welding, but I dont think I have the coordination. I'll probably end up hurting myself lol

BlackLock_A4
01-14-2010, 12:20 PM
Cleeeeeeeean.
I will check back soon for the vid.

Kyle H
01-14-2010, 12:33 PM
Here is a link to the video, vimeo is being slow so it will be a while for it to be watchable though.

http://vimeo.com/8745582

Seerlah
01-14-2010, 12:40 PM
Private video[:(]

CrtchRktRcr
01-14-2010, 12:51 PM
yeah. secret video.. lame.

Kyle H
01-14-2010, 12:56 PM
Now it should work [:)]

Seerlah
01-14-2010, 01:01 PM
Not my cup of cappuccino, but sure does sound mean. Now you need some power to back up that growl[drive].

20vpower
01-14-2010, 01:09 PM
I love how you moved the flange down. That is the most pain in the ass to get off when your taking the exhaust off on jack stands...

Do you get a lot of drone from that? My exhaust is ATP BT DP > stock lower downpipe > 2.5 " pipe welded on at the slip joint > magnaflow 2.5 - dual 2.25 out and I hate the drone!

Kyle H
01-14-2010, 01:22 PM
It has some drone, but it's not terrible. You can still have a conversation on the highway cruising at 70 without raising your voice. When I had the hfc > stock dp cut off after the flex pipe with a turndown it droned WAY worse [:D]



and I definitely need more power, but I need drivetrain mounts, brakes, and money before that happens.

codymack43
01-14-2010, 01:31 PM
would you plan on getting a real polished muffler anytime? Sounds pretty good though!

Kyle H
01-14-2010, 01:34 PM
Nope! Not unless I attract police.

dcampana
01-14-2010, 01:37 PM
nice set up. i have the same outlet, except i painted it flat black. i also have a Dynomax ultraflow muffler on it. i could not imagine with out that how loud my car would be.

Great job though!

Derv
01-15-2010, 02:56 PM
I love it!

Coopa
01-15-2010, 06:06 PM
Damn, that sounds good! And for a pretty good price too.
..can I has your camera please? [:D]

Shhmaudi
01-15-2010, 06:37 PM
Dude sweet job!!! Thats sick how you relocated the flange, ITS BRILLIANT! I want to do the same thing! where did you get the piping? How did you make the bends? I live here in san diego by PB, Would you help me with my exhaust? I am very excited! Please PM me maybe we can do something this weekend? I want to see and hear your car! Sweet wheels BTW. Ill bring the beers!!

h4robkr123
01-15-2010, 08:29 PM
Sounds great man, can't beat the price either! Like others have said that must be a huge boost to your ego when you can tell people that you made it yourself. Plus it looks like it was skillfully made, no terrible welds or anything.

Kyle H
01-16-2010, 07:39 AM
Dude sweet job!!! Thats sick how you relocated the flange, ITS BRILLIANT! I want to do the same thing! where did you get the piping? How did you make the bends? I live here in san diego by PB, Would you help me with my exhaust? I am very excited! Please PM me maybe we can do something this weekend? I want to see and hear your car! Sweet wheels BTW. Ill bring the beers!!
My friend who did the welding is up in Redding CA 11 hours away from SD. I got the bends from here
(http://www.mandrel-bends.com/catalog/), and the straight pipe and hangers from a local exhaust shop. If we can find somebody with a welder I'm totally down to help you out with your exhaust when I get back to SD. [up][up]


The exhaust passed the girlfriend test yesterday, so now as long as I don't get any exhaust tickets it's staying straight piped.

D's Avant
01-16-2010, 07:45 AM
Nope! Not unless I attract police.

Let us know when you get that fix it ticket, especially living in California.

The CHP is going to snag you when you are on some canyon run. I had a strait through exhaust for a while on my MKI GTI back in the last 80's when I lived in California. It lasted a week...

Sounds sick though!!![drive]

Seerlah
01-16-2010, 07:46 AM
Ever think about welding on a merge collector for a cleaner look?

2.5" inlet to dual 2.5" oulets (http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1035_1255&products_id=1676&osCsid=26a61d6c361fd363085054e4ecca09b8)
2.5" inlet to dual 3" outlets (http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1035_1255&products_id=1677&osCsid=26a61d6c361fd363085054e4ecca09b8)

I am sure they can be sought out cheaper with maybe a little longer dual outlets so the welds/merging section can not be so visible, but that's just one place to get them.

Kyle H
01-16-2010, 08:10 AM
I love it!

Of course you do, you built it! [up][up][up][up]

Quattro 4 Life
01-16-2010, 11:23 AM
that sounds pretty mean! i like it, great price too

Shhmaudi
01-16-2010, 12:32 PM
My friend who did the welding is up in Redding CA 11 hours away from SD. I got the bends from here
(http://www.mandrel-bends.com/catalog/), and the straight pipe and hangers from a local exhaust shop. If we can find somebody with a welder I'm totally down to help you out with your exhaust when I get back to SD. [up][up]
Sweet! I have a buddy who has a welder! And welds likea champ.


so we chopped the flange off of my month old cat and welded up a real one piece cat/downpipe, moving the flange down to a reasonable level.
http://khphotography3.com/photos/764411116_JLSFV-L.jpg


I am reallly interested in doing this^^^ relocating the flange a lil farther down where its a little more accessible! Do you think I would need to order any bends from columbia river? It looks pretty much straight from the pic. Could I pick that up from a local exhaust shop?[up][up] Thanks for the help! IM stoaked on it!!

Kyle H
01-17-2010, 01:02 PM
Yeah there is a slight bend off the end of the cat, You'll want to order one mandrel u-bend if you want to just do that. There is also a bend after the downpipe before the flex pipe. If your exhaust is 3" it may not work... the fit was very tight getting the cat/downpipe out with 2.5" pipe and a flange. We can try it though. Make sure you get thicker pipe than 16gauge though... 14 would probably be good for the downpipe.

After we do yours, there is a guy on Audiforums who wants to do a full cat back on his car if your buddy would be willing to weld it up to make a little cash.

Shhmaudi
01-19-2010, 08:03 AM
Yeah there is a slight bend off the end of the cat, You'll want to order one mandrel u-bend if you want to just do that. There is also a bend after the downpipe before the flex pipe. If your exhaust is 3" it may not work... the fit was very tight getting the cat/downpipe out with 2.5" pipe and a flange. We can try it though. Make sure you get thicker pipe than 16gauge though... 14 would probably be good for the downpipe.

After we do yours, there is a guy on Audiforums who wants to do a full cat back on his car if your buddy would be willing to weld it up to make a little cash.
Sweet I talked to my buddy, he said He is down! I am thinking about going to a local exhaust shop and buying some piping.. So possible can have this done this week! I dunno tho about this storm we are gettin tho. Its pretty intense.. Do you know anyone with a lift we can borrow for a couple hrs? Maybe the guy on audiforums knows ofa place??

Kyle H
01-19-2010, 09:45 AM
Great! I don't know anyone with a lift, I'll check with the other guy though. If we can't find one we can get the car up high enough on jack stands to make it pretty easy. Fiber Tech in Santee has the mandrel bends for sure.

Right now I have a strained back and pink eye, so I'm going to need about a week before I do any exhaust fabbing... I can supervise though!

Shhmaudi
01-19-2010, 12:11 PM
Great! I don't know anyone with a lift, I'll check with the other guy though. If we can't find one we can get the car up high enough on jack stands to make it pretty easy. Fiber Tech in Santee has the mandrel bends for sure.

Right now I have a strained back and pink eye, so I'm going to need about a week before I do any exhaust fabbing... I can supervise though!

Damn Hope you feel better! Question. Your stock DP was 2.25"?? and you re did it to 2.5? an it barley fit??

O2VW1.8T
01-19-2010, 12:26 PM
That's my friends welder... It's a Hobart 140. He loves it, I don't know much about it. I've heard great things from everybody he talks to about it though.
[IMG]http://i290.photobucket.com/albums/ll278/Volvosporter/DSC00644.jpg?t=1255830595[/IG]
[IMG]http://i290.photobucket.com/albums/ll278/Volvosporter/DSC00643.jpg?t=1255830689[/IG]

Ahhhh small welders I LOVE them I have a lincoln 135 that size and i did my whole AWD swap in my GTi with it, build FMIC piping, exhaust piping never had 1 crack. I love simple mig welding[up]

Kyle H
01-19-2010, 09:27 PM
Damn Hope you feel better! Question. Your stock DP was 2.25"?? and you re did it to 2.5? an it barley fit??

Thanks man. The problem is that you have to pull the cat/downpipe out of the top as one piece, so even though it's only 1/4" bigger diameter, you have to twist and turn it to get it out since you're adding another ~18" in length. Another 1/2" may make it too big, but I'm pretty sure it would work.

Kyle H
03-01-2010, 03:36 PM
After a month and a half in San Diego and one illegal left turn ticket, I haven't gotten any attention from the police about my exhaust. [:)]


Shhmaudi, you still want to do the work on your car?

champion
03-02-2010, 11:01 AM
any pics?????

Kyle H
03-02-2010, 12:00 PM
I can't believe I didn't post these here!

http://khphotography3.smugmug.com/photos/764693655_CZTDF-M.jpg

http://khphotography3.smugmug.com/photos/764692378_RBN39-M.jpg

ThatA4T
03-02-2010, 12:04 PM
you did i think they just disappeared

Kyle H
03-02-2010, 12:19 PM
Thanks, found them. I got rid of my old domain name so now the hyperlinks are dead.

champion
03-02-2010, 12:28 PM
pics of the exhaust system?????? underside

Kyle H
03-02-2010, 01:09 PM
No pics from underneath... here is the exhaust minus one bend and the tip I think...

http://i146.photobucket.com/albums/r261/snowmanhitman/photo2-1.jpg?t=1267564107