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  #1 (permalink)  
Old 08-19-2013, 09:59 PM
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DIY mandrel bent exhaust in a box

After putting 275/40ZR18's on the back of my 64 Impala I knew it was going to be a tight fit running the exhaust. The original 2" exhaust was rubbing on the inside of the old 245's I had in back.

I took out all the old exhaust after putting headers on the car. I through a couple FM Delta Flow 50's I had from another project and dumped them right after the muffler under the car. It was LOUD as I knew it would be. I did it that way just to get the car together enough to drive it.

After being annoyed long enough and not wanting to go any more deaf than I already am I decided it was time to run the exhaust out the back. There aren't any places that do mandrel bending in my area and knew it would be quiet a chore to bend an exhaust that didn't hit the tires since the clearance in back is so tight.

I had bought some 3" mandrel pipe from Mandrel Bending Solutions out of Maryland before and was quite happy with them. They had a deal on several 45, 90 and 180 bends along with a few 5' strait lengths. The idea I had was to build a custom exhaust cutting all the angles I needed and welding them together like a set of custom headers. I figured I could do a better job keeping the tolerances as tight as I could than a shop using a bending machine.

I used their aluminized pipe and finished the welds by grinding them down with a flap wheel to make it look like a single piece of pipe and painting them with silver VHT high temp header paint. It ended up being a lot of work but I am really happy with the results. A couple of days later of crawling around the floor on my back and this is the results.

I think anyone with a little bit of patience could do this. All I used for cutting the pipe was a 4" grinder and several .045 cut off wheels. I ordered two extra 180's because I didn't want to be short but ended up having quiet a bit of pipe left over. I'm very happy with the end results.




Untitled by dennydog, on Flickr

Tacked up and ready to weld the first side.


Untitled by dennydog, on Flickr

The finished exhaust from the back.


64 Impala dual exhaust by dennydog, on Flickr

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Old 08-20-2013, 03:48 AM
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looks good, how does it sound?
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Old 08-23-2013, 08:10 PM
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I'm happy with it except for the sound at idle. It seems as though it has the dreaded Flowmaster hollow sound I've heard other people mention.

I think it might be because I cut the inlets on the muffler bigger and ran the 3" from the collector strait into the muffler. I've run 40 series on a couple other vehicles and never had the "fluffing" sound I am hearing now.

I think I might reduce the pipe back down to 2 1/2" before it goes into the muffler. I think this might take care of it. If it doesn't I may look at putting something else on the car. It sounds great otherwise.
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Old 08-24-2013, 05:16 AM
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That's awesome! I am doing the same thing this winter. I just finished building a jig for my chop saw to cut the mandrel bends accurately and on the bend radius. I also had to build a new trans cross member that will allow the pipes to go thru. I will try and post a picture of it this weekend.

Anyway, thanks for posting, its good motivation for me to get mine done!
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Old 08-24-2013, 07:01 AM
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glad to see you using 3 inch exhaust
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Old 08-24-2013, 04:29 PM
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Quote:
Originally Posted by 38project View Post
That's awesome! I am doing the same thing this winter. I just finished building a jig for my chop saw to cut the mandrel bends accurately and on the bend radius. I also had to build a new trans cross member that will allow the pipes to go thru. I will try and post a picture of it this weekend.

Anyway, thanks for posting, its good motivation for me to get mine done!
Yeah, it really wasn't that hard and was worth the time doing it this way. It would have been a lot easier if my dad hadn't sold our Ellis saw that we had. It had the upright band saw attachment too. Even a chop saw would have made it easier.

I'm still thinking of trying a different muffler. It's ok for now but want to hear how something else would sound.


Quote:
Originally Posted by vinniekq2 View Post
glad to see you using 3 inch exhaust
Actually it's 3" from the collectors directly into the flowmasters and then 2 1/2" from the muffler all the way back. Probably plenty for the engine I have in there now. A full 3" would be REALLY tight. The only way to fit that would be to run oval pipe.
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Old 10-30-2013, 06:22 PM
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Mandrel Bend Cutting Fixture

Hey, I finally got around to working on the exhaust for my 38 Plymouth. I bought some Mandrel bends and I made a fixture for my chop saw to cut the mandrel bends on the bend radius center line. I'm so happy with the way it worked that I wanted to share the pictures.











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Old 10-30-2013, 06:33 PM
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I really like your jig! That sure beats the handheld grinder method I used. My dad used to have a Elis band saw but he sold it for unknown reasons????? I will have to build something like that next time.

Curious where you got the mandrel bends? Is that aluminized tubing?

I painted all my seams with silver VHT header paint and it's still holding up to the heat. It matches the pipe fairly well and beats having the seams rust.
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Old 10-30-2013, 06:43 PM
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Mandrel Bends

Quote:
Originally Posted by 64SS327 View Post
I really like your jig! That sure beats the handheld grinder method I used. My dad used to have a Elis band saw but he sold it for unknown reasons????? I will have to build something like that next time.

Curious where you got the mandrel bends? Is that aluminized tubing?

I painted all my seams with silver VHT header paint and it's still holding up to the heat. It matches the pipe fairly well and beats having the seams rust.
Thanks! I got the mandrel bends from Columbia River Mandrel Bends on the web.
https://www.mandrel-bends.com/catalog

Yes, they are aluminized steel. I plan to paint with the silicone coating for exhaust wrap and then wrap with the titanium exhaust wrap.
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Old 10-30-2013, 06:57 PM
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I'll have to compare prices next time I need tubing. I would like to get into doing custom exhaust. It seems as though there would be a pretty good market for that sort of thing.
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Old 10-30-2013, 08:49 PM
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Mandrel Bend Jig

Quote:
Originally Posted by 64SS327 View Post
I'll have to compare prices next time I need tubing. I would like to get into doing custom exhaust. It seems as though there would be a pretty good market for that sort of thing.
Yea, if you get into doing exhaust systems let me know, I will build you a jig!
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Old 10-30-2013, 09:12 PM
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i like your chop saw fixture too. downloaded the pics and will be making one of those soon.
we do one off exhaust systems and headers and need to cut partial bends

fyi, all mandrel bent custom exhaust systems are built in pieces like that.
unlike a crush bender, you can't reinsert mandrel bends back into the bender.
a good bender operator can figure a bend or 2 by eyeballing the bends.
but after those bends, a true custom exhaust has to be pieced together.

69 dynacorn mustang header w/ coyote motor


09 fusion turbo header
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Old 10-30-2013, 09:59 PM
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Thank you for posting ogre. Nice looking headers. I did not know they couldn't reinsert pipes back in to a mandrel bender.

It seems like tools that were once only available to big companies are getting more affordable to the small guy. I have read about 3d scanners and wondered if a guy could scan the bottom of a car or possibly an engine compartment and do a 3d model before even cutting any pipe.

Portable 3D Scanners for 3D Scanning | Handyscan 3D by Creaform

Kind of dreaming I know. Would be pretty cool though.
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Old 10-31-2013, 09:39 AM
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those pipes are simply amazing. thank you for sharing
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Old 11-03-2013, 01:57 PM
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Thanks for posting the jig pics.

I'll have to try something like that next time.
I cut all my bends with a zip cut disc.

I did make up a jig however to draw accurate lines.
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