Mandrel Bent Exhaust

[Dashman]

I'm having trouble finding a source for custom mandrel bending an exhaust system with 409 stainless steel in New Mexico. In about 2000, I bought pieces and had them welded together for my '81 Silverado. In about 2010, I had 2 "front pipes" bent to replace the previous pieces that were welded. I still kept the welded tail pipes. The website for the company that I used is no longer in use and I can't remember the name of the company, but they were in the north east. I've also been told that no one does mandrel bending in NM. I've designed a system for my Dad's '72 K10, and I recently emailed this guy in the north west sheets of my design. He said he can't do the S-curves that I've designed because he needs at least 5" between the bends. I said, "flip the pipe, do the math, and bend the tube for the 2nd bend from the other end". (Maybe some of you have also seen the you tube video of the guy that does this on a bender for 2" pipe and less?) He said, it's not possible. Can anyone recommend a mandrel bending shop near NM? ...like AZ, UT, CO, KS, NE, or TX? Shipping cost is a concern on (2) pieces that are 60" long. Thank you.

[Joyridin]

So what diameter pipe do you want, and how long? Most places that do mandrel bent piping use 304 stainless because it does not rust like 409. Where you live though, I doubt it matters.

[Dashman]

That's also what I said. I wanted the 304 for road salt corrosion resistance, what this guy said is, Magna Flow uses 409 and only show trucks use 304. What I figure is the 304 is harder to bend with more chromium and nickel, and would require a heavy duty bending machine not the lesser expensive type. I'm willing to go with 409 stainless steel to just get it done. The welded up pre-bent tubes on my '81 K20 are 304, and the bent front tubes are 409. A person can see my tailpipes, but not my front pipes. Both stainless steels look in good shape after 20 and 10 years for the 304 and 409, respectively. No offense intended, but I need a bending shop and bender person *not more advice on type of stainless steel.

[HalfBrit]

Have you thought about sourcing mandrel bend sections (45/90/180), then have them welded? Long or short radius are readily available from various online suppliers. I used short radius 90's from this shop:
https://www.aceraceparts.com/

[Accelo]

https://www.gbemandrel.com/

[HO455]

Originally Posted by Accelo

https://www.gbemandrel.com/

I know those guys! Bought 90* & 180* bends and truck lamps from them before. They're usually at the Portland Swap Meet every year.

As far as the 60" pieces why not do 2 smaller pieces and connect them with truck clamps or with these...

https://www.gbemandrel.com/2-1-2-marman-assy-409ss.html

[72SB]

You can buy mandrel bend in various angles and straight pipe pieces in 304 or 409 at places like Summit and build a custom exhaust

[Joyridin]

Originally Posted by Dashman

That's also what I said. I wanted the 304 for road salt corrosion resistance, what this guy said is, Magna Flow uses 409 and only show trucks use 304. What I figure is the 304 is harder to bend with more chromium and nickel, and would require a heavy duty bending machine not the lesser expensive type. I'm willing to go with 409 stainless steel to just get it done. The welded up pre-bent tubes on my '81 K20 are 304, and the bent front tubes are 409. A person can see my tailpipes, but not my front pipes. Both stainless steels look in good shape after 20 and 10 years for the 304 and 409, respectively. No offense intended, but I need a bending shop and bender person *not more advice on type of stainless steel.

I wasn't giving advice on which stainless to use. I clearly stated "Most places that do mandrel bent piping use 304 stainless", since your post stated you wanted 409.

[Dashman]

Thank you all for your responses! Responses are better than no responses. Circa 2000 I ordered pre-bent 304SS pieces for my '81 K20 (it's in my original post). Since then I personally welded the mild steel mouth piece on a Duramax Garret turbo to a 3.5" OD 304SS with a 15 degree bend for a custom down pipe with my 120v MIG welder. So I could go that route, but this time do the welding myself. Circa 2010, I had a company mandrel bend (2) front pipes from 409SS for said '81K20 (it's in my original post). That design had S-curves in it.

Yes, GBE, Steve, that's the one that told me he can't do S-curves without at least 5" between the curves, and that 304SS isn't necessary. Nonsense I say! I tried working with him, even settling on the 409SS.

Check out this guys video before and after the 6:08 mark:
https://www.youtube.com/watch?v=EmLHEvlrB8k

I would still like to know of shops you've used in the SW that can do mandrel bending. Thank you!

[truckster]

I built my 2.5" duals just over a year ago using 304 stainless and Magnaflow stainless mufflers. The 304 stainless still looks beautiful, but the mufflers are already showing some surface rust.

To build mine, I bought the straight and curved pieces and sectioned the curves where I needed to. I went from the 2.5 rams horns and exited behind the rear wheels, with a crossover between the transfer case and the mufflers. I used my Hobart 140 with tri-mix. The gas has gotten really expensive because helium is really expensive now, but the whole thing cost me about $800 and a couple of days' labor.