Newbie X Crossover Exhaust Project

[pontiac]

I just found this board thanks to another new guy here P455
I've been reading and learning alot that should really help improve my welding skills.
Thanks to everyone here..

This was my last project..
It's an X style exhaust crossover for my 70 Firebird.


http://www.pontiacs.org/modules.php?name=projectx

[Will]

Scott,
Great looking exhaust system. I enjoy seeing sombody innovate with what they have on hand to get a project done... But all that hack saw work must have really worn out the arm!

[pontiac]

Thanks.. It was a bit of work cutting those by hand..
Next time I'll buy a chop saw :)

[Rocky D]

That would have been tough to do even for a pro...also TIG would have made the job easier. Good job!

[pontiac]

Thanks Rocky!

I'm not to prowd about the welds around the flanges..
I found it a bit tough laying down a good filet welding 16gauge to 1/4" going in a circle :)
http://www.pontiacs.org/content/70bird/pics/xflanges.jpg

Any comments on what causes the brown ash around the beads?
http://www.pontiacs.org/content/70bird/pics/xincar2.jpg

[Hobart Expert Rock]

HI SCOTT.........WELL THE BROWN COULD BE A COUPLE OF OBVIOUS THINGS LIKE NOT ENOUGH GAS, CONTAMINATION, PLUGGED ORAFICES IN THE GAS DEFUSER ETC....... YOU GET THE IDEA......WHAT KINDA OF WIRE WAS IT ANYWAY, WERE THEIR ANY PINHOLES IN THE WELDS THAT WILL ALLOW EXAUST GASSES TO CREAP BACK INTO THE DRIVING COMPARTMENT.............DID YOU PRICE THE X CROSS OVER TUBES FOR THE EXAUST OR ARE THEY OBSOLETE.......... HOWEVER I THINK IT LOOKS LIKE A WELL LAYED OUT PROJECT..........HOW MUCH TIME YOU GOT INTO THIS PROJECT.......................ROCK
SSCOTT@MILLERWELDS.COM

[pontiac]

I'm with ya on the gas flow..
I'll double check my pressure and give the gas defuser a good inspection..

Would a flow meter be a good addition for a small mig 110 mig setup or not?

So far I've only found 1 small pinhole on the X portion of the exhaust.. everything else is solid.. They are easy to spot after you get a few miles on the car and the little jets of soot start showing.

I was carefull to go over everything as I went touching up any possible pinholes as I welded things up.

I spent about $115 on materials for the job.. thats 8' of 16 gauge aluminized 3" pipe and 2 180 deg 16g 3" mandrel bent pipes
The mandrel bends were $30 each and the pipe was $5 a foot.

I know the price pr foot is a bit high but the same pipe from Summit is the same cost after shipping.

If someone in the Seattle/Tacoma area know where to get the tubing without the exhaust shop middle man I'd be happy to know.

This compares to $189 for the X kit from Dr Gas..

You can get just the X for $89..


Total investment with extra tools I bought comes to about $140
so I only saved about $50.. If I was doing this just to save $$ I wouldn't have done it.. I just like building stuff :)

Time spent.. about an hour on design, another 6 or so in real work time. 2 Saturdays when you figure in the beer breaks, lunch breaks, and general farting around in the shop.

I tend to waste allot of time whenever I get under the car because I keep wandering off and inspecting other stuff while I'm under there.

[Hobart Expert Rock]

NICE JOB.........NO YOU CAN'T COUNT BEER BREAKS, NAPS, ETC. INTO THE EQUASION........ THE NICE THING IS YOU DID IT YOURSELF, AND SAVED MONEY.............WHAT A GREAT COMBINATION........GET THE LEAK FIXED AND YOU SHOULD BE GOOD TO GO.....................BE SAFE...................ROCK
SSCOTT@MILLERWELDS.COM

[s15laynrubba]

Wow, good job Pontiac.I am fixing to start on my exhaust system saturday morning. I believe building the exhaust for my truck is gonna be a PITA because of angles and obstructions.I will have to run the exhaust from the driver side collector to the passenger side of the truck and then run it back to the axle because of the gas tank hogging up too much space.I know i shouldve bought a fuel cell!:rolleyes: . The passenger side will be a breeze.I am going to borrow your X pipe design.;) I will post some pics when i get finished.....Jay

[JeramyK]

That turned out great, Pontiac ! Looks awesome. :)


Originally posted by pontiac

Any comments on what causes the brown ash around the beads?
http://www.pontiacs.org/content/70bird/pics/xincar2.jpg

I was wondering this too. I have some spare exhaust tubing that I cut off my 79 Camaro that I practice welding on. I get the same brown ash around the beads. Usually some of it will wipe off with a cloth. I haven't really tried cleaning it with a solvent yet though.

Could it be the type of metal ? It seems that regardless of how the weld area is prepared it turns out the same way. I've tried changing gas pressure from 22 - 30lbs. Unless it needs to go higher.

-Jeramy

[10secBu]

That's a good looking system you built there. Exhaust work is a real pain, especialy if you don't have the luxury of owning a lift.

I too just installed a "X" pipe system, although I used the Dr. Gas system...3 1/2" in/3" out into long case Dynomax UltraFlow welded mufflers. I also chose to build tail pipes from scratch as I'm tired of the dust that gets kicked up from turn downs in front of the axle. I also wanted the car as quiet as possible. This system was quite expensive at about $750 in parts till I was done. It took 6 mandrel bends for the tail pipes at over $30 each, $240 for the Dr. Gas kit, $15 each (used 4) for the flange kits, plus pricey shipping from Dr. Gas on the opposite coast. Oh yea, $100 each for the mufflers too:rolleyes: .

http://www.qis.net/~geislert/drgasxpipe.jpg

http://www.qis.net/~geislert/dynomaxmufflers.jpg

http://www.qis.net/~geislert/newexhaust1.jpg

http://www.qis.net/~geislert/newexhaust2.jpg

http://www.qis.net/~geislert/tailpipes1.jpg

http://www.qis.net/~geislert/tailpipes2.jpg

http://www.qis.net/~geislert/tailpipes3.jpg

http://www.qis.net/~geislert/tailpipes9.jpg

http://www.qis.net/~geislert/tailpipes11.jpg

http://www.qis.net/~geislert/tailpipes14.jpg

http://www.qis.net/~geislert/tailpipes15.jpg

http://www.qis.net/~geislert/tailpipes16.jpg

http://www.qis.net/~geislert/tailpipes17.jpg

Man, were those tail pipes a pain to fit in there between the upper control arms, the axle tubes and the anti-roll bar which really took up some much needed space to get over the rear. I chose to Mig weld the front half of the system for speed purposes, but Tig welded the tail pipes for a much cleaner, neater look. This winter I plan to remove the system and have it ceramic coated to match the headers.

[Dubliner]

where did you get the mandrel bent pipes, I'd like to make a roll bar for my convertible, unfortunately I suffer from the same condition as you, and could probably buy them cheaper, but you dont learn much that way, tx, Neville ps could you get them in stainless?

[Harsany]

Originally posted by Dubliner
where did you get the mandrel bent pipes, I'd like to make a roll bar for my convertible, unfortunately I suffer from the same condition as you, and could probably buy them cheaper, but you dont learn much that way, tx, Neville ps could you get them in stainless?

DON'T USE EXHAUST TUBING FOR A ROLL BAR!!! You'll need at least 1-3/4 OD x .120 wall HREW tubing. DOM is even stronger. I've seen guys use weldable pipe elbows to make their bends, but you best choice is to find someone with a tubing bender.

[pontiac]

Oh yeah.. Do not use exhaust tubing for a rolll bar..
It won't hold..

I've never heard of a stainless bar either. Just mild steel or 4130 chrome moly tubing.

1 3/4x .134 for mild or 1 3/4x.083 for 4130

A 4130 bar would need to be Tig (GTAW) welded pr NHRA rules.


I don't know if a tool like the compact bender from HF or Grizley would bend that stuff or not..

The bender from Pro-Tools will set ya back about $500 with dies but you could always bend tubing for your friends for a small fee :)

As for the exhaust mandrel bends.. (for exhaust work only)

you can either order them from Summit, Jegs or call around local performace shops and ask who has one.

A mandrel bender is a $30,000+ tool so not many shops will.

[Rocky D]

Originally posted by JeramyK
That turned out great, Pontiac ! Looks awesome. :)



I was wondering this too. I have some spare exhaust tubing that I cut off my 79 Camaro that I practice welding on. I get the same brown ash around the beads. Usually some of it will wipe off with a cloth. I haven't really tried cleaning it with a solvent yet though.

Could it be the type of metal ? It seems that regardless of how the weld area is prepared it turns out the same way. I've tried changing gas pressure from 22 - 30lbs. Unless it needs to go higher.

-Jeramy

There probably is a chemical reason why the ash appears...but in 35 years of MIG welding I still don't know why...to me, it is a non-issue....no biggy...it just happens. :)

[INTP]

Nice work. I thought of doing the same thing on my mustang. The only thing different is I was trying to imagine a way to widen the curved pipe where the two pipes meet (middle of the X), to avoid restriction and turbulence.

I did a custom side exhaust on the cheap to deal with interference issues with my panhard bar. (a re-engineer of the stock mustang 'quadra-bind' rear, using Grigg's parts). I used half a U-bend and one J bend per side to get it to exit just in front of the rear tires. It wasn't easy, and didn't turn out exactly like I hoped. I found out that cutting mandrel bends and getting everything to line up right when it's welded is not (NOT) easy!

[banzaitoyota]

Mandrel bends are also available at www.burnsstainless.com

[pontiac]

Theres a Question for 10secBu (Nice job BTW)

What did you use to cut the mandrel bends?

I was using a normal pipe cutter (from HF :) ) on the straight stuff and a chain cutter (also from HF) on the bends..

It worked ok but you had to be sure it was on straight or it would spiral down the pipe.

The chain cutter did a good job but every cutting wheel was chipped by the time I was finished.

[10secBu]

Hey Scott,

I used a Dewalt 14" abrasive cut-off chop saw with a blade 50% worn...just enough to cut completely through the tubing. I find the smaller diameter of a worn blad flexes less and gives more accurate cuts. I am planning on replacing it with one of the carbide tip saws somethime down the road. I'm tired of the damage the sparks create.

Wow, it must have taken quite a long time to make your cuts using those manual methods...you got more patience than me and I thought I did things the hard way;) :D .

[pontiac]

I would have killed for a chop saw by the end of the day :)
Cutting the X openings with a hacksaw was the worst part :)

I have a Milwaukee chop saw now but I wish I had a bandsaw.

[INTP]

Hey, for that $50 you saved, you can get a chopsaw from Harbor Freight. They have a 14" that's often on sale for $49. If it isn't on sale now, it soon will be... I have it and it works fine.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=47003

[RawkRash]

If you look in the Jeg's catalog, Flowmaster has universal tailpipe kits for $69 in 2-1/2 and 3 and I think 3-1/2" diameter. It's nice heavy aluminized tubing with mandrel bends. Each kit comes with 4 pieces of tube that started out 4 or 5 feet long and each one has a single bend in it.

One starts from straight and bends about 75 deg to point up toward over the axle. The next one has a 110 or so bend to point back down after going over the axle. The third has another 75 deg bend to once again point straight back and the last one has a 90 to point out the side.

They're intended to be cut to length and clamped together (each has an expanded end) to fit any pickup.

I used a couple of these kits to fab up a complete exhaust system for my Wrangler when I swapped to a V-8 a few years back.

It's a great source of cheap bends and good tubing. The mandrel bends are nice and round and can be cut anywhere and rotated and welded back together to make a nice system.