cracked mani - need advice/opinions

First off this is not on my 240. its my turbo civic…
Im not making this post to be harped on about what was done wrong etc…
I bought a kit from vibrant for making log manifolds… it came with the head flange, 2x 90 deg, 2x 45 deg and 2x 12" log pipes
I built the manifold myself with my mig welder for the most part… when i had finished the log i needed a port cut out, and a tube to go from the mani to the flange… I didnt have the tools nessessary to finish my manifold so i brought my civic to a shop to get finished (i.e. mounting turbo and mating up the 3" dp… the remainder of the setup was completely done by myself…

So the shop i took it too suggested using exhaust pipe to go from the manifold to the flange… it would be considerably easier to use a circular pipe for this since the 14b turbo flange is circular as well… i had asked the shop if they should use a pipe with a thicker wall, because i figured exhaust pipe isnt right to use, c’mon… so he had told me, yes it will be fine, np etc…

Probably 1500 km max put on the manifold. everything is going good… i noticed a slight hair crack in the pipe so i put a bead of weld across it. and braced the flange to the manifold in the front with a flat piece of steel…

Last nite i changed my oil lines, and put SS braided on from cisco… drove maybe 10k, got gas, popped the hood, took a look, no leaks, no problems…

Pull out of the gas station, drive maybe 200m, and it goes super loud. i shut the car off near high park… pull over, and before even popping the hood i tell my buddy the turbo probably fell off… sure enough it did… so i didnt want to get towed since i was only 10-15 min from home… i knocked on some persons door. got some coat hangers and lifted the turbo back up and strapped it to the mani, disconnected the cold side charge pipe so getting air into the motor wouldnt be a problem.

Got home fine… and im trying to figure out. whose fault is this…
I then call the shop and found out he used flux-core to do his welding which isnt too great to hear. my question is, should he be at complete fault?? and if the shop or myself welded it back together and braced the shit out of it… should it be okay?

This is a little pic i made to show an example of the crack…
http://img.photobucket.com/albums/v719/brandons13/manicrack.jpg

my final question is, by the looks of the design of the manifold… where would the most stress be on this manifold… i figure its not where it cracked… wouldn’t the tubes going to the head flange let go first?? which leads me to believe my welds are better than a shops that i paid them to do…

any suggestions are appreciated alot, considering im asking for help on a 240 board. 8)

Thanks in advance guyys…[/i]

was this kit stainless or mild steel? how thick a wall was the exhaust piping ? was the collector flange straight down or out an an angle? MIG welding is for making jigs and garbage bins… this should all have been TIG welded. ( the latter is my opinion )

But the main reason it failed is you went the cheapest route posssible to make one of the key components, with the highest stress… you pretty much got what you built/paid for.

Finally you didn’t really ask a question that required allot of ’ suggestions’…

Your question is self answering: weakest point is where it cracked… how hard is that to understand…

i say its your fault hence you gave them the ‘okay’ on the exhaust pipe, unless he promised you it will be ok, would rip that exhaust pipe crap off and get a thicker piece which is the same material as the rest of the mani that you made, weld it on properly

should have been made out of VERY thick piping, and MIG gas welded, I would not flux core weld my lawnmower

what Diameter pipe did he use?

If you want I can reweld a new very thick steel pipe on