Artech Downpipe crack. Will a repair hold up?
 

So I have probably less than 1000 miles on my Artech side-mount setup. All cruising miles, no track or anything. Got a nice crack that developed last week and im wondering if a repair will hold up? I'm not even going to E-mail Abe about this because I want to get the downpipe out, repaired, and re-installed all in the same day. This way I wont have to take up space in my work's garage for too long. Thoughts?

https://www.miataturbo.net/attachmen...ine=1426432547

Zoomed in

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I would reweld, then work on a transmission brace.

What shuiend said. Also, I think Abe warranties all his stuff, it'd be foolish not to take advantage of that.

Cool thanks. I just started looking around at braces... $399 for the FM brace... Yikes better start tucking $$ away haha

is there a flex pipe on this?

Yeah further down

https://www.miataturbo.net/attachmen...ine=1426434639

What in the world you looking at thats $400? I thought they were like 30-40?

edit: lars is talking about this right? http://www.flyinmiata.com/index.php?...umber=06-97577

I thought about it originally but considering how much it would cost me to ship it and the time to send it, wait for him to repair it, and then send it back wouldn't be worth it. If he will send me a credit for a repair I have done though, It would be worth contacting him about that

Oh wow if that is all he was referring to, I'll order that up today!

Issue is that's for a fm manifold and dp. Idk if its going to be plug and play. May have to make your own that fits your setup.

Yeah that's true too... Doubt the positioning of the exhaust would be close enough for it to work. Might be a good starting point to though and try to modify it to work with my exhaust

Yeah something like that.

But that is the correct concept. Something that mounts at the tranny, and holds the downpipe up, while allowing it to expand in length. I made mine work with custom exhaust by cutting and re-welding the FM bracket so the clamp was in correct location. Tacked while on car.

Why did i have to see this after putting a deposit down on similar setup? Subbed

Lol I wouldn't sweat it too much. I'm 1000% happy with the entire setup. Luckily it should be an easy repair... Make sure you add a brace to yours and you should have no trouble!

You flex pipe looks to be In a similar location as mine. Which means the fm brace would bolt behind the flex piece, rendering it useless.

Is there anything else that would work?

My next project is to use an exhaust band clamp to make a brace. It supposedly spreads the weight out better.

Just clamp on an exhaust clamp, and use a 25mmx3mm mild steel strap bend and drilled to bolt the clamp to the box, in front of the flex.

(thats 1"x1/8th")

Yeap. Do this, and reweld the weld that's cracked.

Yep pulling the downpipe out tomorrow and bringing it to be repaired. I will get the clamp on this weekend

Check out my build thread for the brace I started. I'm going to try and finish it today or tomorrow.

Nice thanks! Subbed

Brian, I'm sorry about the cracked downpipe. As far as I know, this is the first case. If you send it back, I'll have it back by the next day. I understand if you don't want to deal with the transit time. Just email me the bill and we'll work it out.

Did it by chance feel forced when installed? Did everything line up ok? I'm just trying to figure out what could have gone wrong, and what I can do in the future to prevent it. FM uses a brace because they don't use flex joints. A brace shouldn't be needed if a flex joint is used, but I'll look into it. I see you used new motor mounts when the replacement motor went in. Highly doubt that they've gone bad already, but it wouldn't hurt to check them.

edit: have it ready/welded, not back to you.

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Thanks for chiming in Abe! Just got your e-mail as well but figured i'd just reply here.

I Ripped the car apart today and took the downpipe to get repaired. Guy said everything else looked good and had no other concerns about the other welds. The downpipe was routed perfect and not contacting anything. I was actually surprised by how the downpipe v-band flange and exhaust v-band flange mated PERFECTLY together once I finished tightening the turbo downpipe stud nuts. Oh yeah I dont believe I ever mentioned how big of a PITA it is to have studs here... If this downpipe ever comes back off, they will be replaced with bolts. The welds were spilt down the middle, almost completely all the way around. It was just barely hanging on by maybe 1/2". I'm just as stumped as you are here!

All he wanted for the work was a case of Molsen Golden so $20 im not worried about haha.

Pics:

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In other news... Car developed an intermittent misfire/ stumble (to the point of almost stalling at idle)... Not sure what that could be but I am wondering if it has to do with the COP's I picked up used back in October. I have been meaning to pull the harness apart and check/re-do the connections. Owning a Turbo Miata is such a joy sometimes, isn't it? I could have never done this without a daily... and to think that daily turbo miata was my original plan.... hahaha yeah's funny

I dailied a turbo miata for YEARS.

Misfire, first thing new plugs. 1/2 the time that fixes it for me.

I know it's possible and has been done... But I just couldn't imagine doing it with all the headaches that come along with it haha. I'm sure it gets to the point where you have it dialed in enough where it's reliable but I still would be on edge about it.

Plugs were brand new ngks back in october

I had a used COP that would occasionally go out. Finally it completely died. Ran on 3 cyl for a bit and was confused why I was down on power.

I used to run 7's for plugs, they would foul out all the time. Started running 6's. If I drove it hard like normal, they were ok but still would foul out occasionally. I think a super hot ignition system 6's would be fine. I have 6's in my motor right now. I never had good luck with 7's not misfiring after a few months.

Also regarding reliability for a DD turbo miata. I built and tuned mine FOR DDing. So new cooling system, upgraded fans, built motor, Cast turbo manifold, huge IC, super conservative tune (rich and retarded), turbo bolts wired together, CAI, 16 gauge steel exhaust that's quiet and has plenty of hangers, insulated cabin, hardtop, etc. It was very reliable. In 5 years, it left me stranded once. The once was a wire that I had damaged, repaired, and it failed again as my repair sucked. So it was my fault. And I ran 17-20 PSI during that time, 100% duty cycle on 550s.

Awesome fix and price for the repair!

OTOH, I can't believe I gave Abe his first prop!

Well, if he would hang out around here with us cool kids rather than the Honda crowd, we'd have more opportunities to prop him :nono:

Heh, just yankin' your chain Abe, I love my ARTech goodies. Nicest thing in my car by fair margin. :bigtu:

Hmm interesting on the plugs... I picked up a set of 6's today because for $10 I think it's worth it to have a spare set in the glovebox just in case... If I have it happen again I'll swap them in haha

I wish I could get my car to the point where I trust it completely... Lol I don't have the cash around to build a spare forged motor. Just praying this one holds up for a while. I still need an aluminum rad and take it to get on the dyno... I'll feel quite a bit better after those things get done lol

Well I guess the answer to "Will it hold" is a big fat NO!

I'm seriously so down right now... Just wanted to cruise into work on the first nice day in a while... on my birthday.... and this shit happens again. I'm seriously at a loss right now and I dont know what I should do now. Should I have another DP made up? Should I have this one repaired again? Should I have it repaired and modified in some way to try to prevent it from happening again? Something is going on making it crack and I really really wish I knew what the cause was so I could make right whatever the wrong is...

https://www.miataturbo.net/attachmen...ine=1428320779

there has to be stress on that pipe once installed, then once it expands in heat, it's too rigid and snaps.

Think it would be possible to split the pipe in half, and add in a 1/2" or 1" ring as a spacer, and possibly take some stress off of it? Maybe I'll send it back to Abe this time and see if he has something else he can try for it. I just cant believe it happened again in under 100 miles this time.

I'd suggest gussets, like turbotim did. Something like 1/8 or even 1/4" diamonds of material welded across the stress point.

https://www.miataturbo.net/attachmen...ine=1428331644

I think even after that you'd want to look else where to find why it's cracking. Looks like you had the entire circumference rewelded, so I'd sort of trust the weld to survive under normal conditions.

Are you motor mounts in good working order? I'd try a brace further down too. Keep in mind FM's brace will NOT work, I've already asked, it's mounted after your flex pipe.

Yeah that turbotim deal looks nice. Hopefully Abe will get back to me so we can figure something out for it. I just never expected it to happen again so quickly. When the repair was done the first time, they re-welded completely all the way around and he said he used a thicker weld to try to make it stronger. This time I will have to make some kind of bracket as soon as I install it. My motor mounts are brand new mazdaspeed mounts installed when I swapped the motor in back in October.

From this side of the internet, it looks like there is no brace, and since it's cracked twice in the same spot FAST, it's pretty obvious the stress at that location is really high for some reason. If you make that weld stronger, there's a fair chance the pipe will crack at the next-closest weld.

My recommendation is to add a brace to take the load off the downpipe. If that was 16 gauge mild steel tube it wouldn't be cracking since it could handle that load no problem. But it would be heavy and not as pretty. If you want thin wall stainless, you can't put huge loads on it and expect it to last.

Treat the symptoms- brace around the weld/reweld.
Solve the problem- take the loading off of the downpipe.

Noted. Thanks

Definitely going to be adding a brace immediately after having it fixed. Not going to risk having it happen on me a 3rd time.

No problem, I know that sucks having to keep pulling it! When I was turbo I always ran mild steel 16 gauge as it was cheap and reliable and no brace required because wall thickness was like .065". But alas my exhaust system probably weighed at least twice what yours does and certainly was not as pretty!

I really dont care much about it looking nice.. I really just want to be able to drive the thing without worrying about anything going wrong. I wouldnt be opposed to having an exact duplicate made in a thicker walled piping BUT I highly doubt Artech would eat the cost of that. I'm sure the materials are more expensive and the labor time would be long.

How did we conclude this is thin walled? Might it not be 16 GA SST?

I measured it with a micrometer.

No, I don't know what gauge it is actually, maybe the guy who made it can chime in? Or the OP can measure it and post. Actually a good point, if it IS 16 gauge then damn, I don't know how you keep breaking it!

Abe just got back to me so now I just have to pull the pipe back out and get it shipped over to him

DP Is out once again... Off to Abe tomorrow!

Installed/ Uninstalled pics for Artech. No contact with anything anywhere :-/

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You need a god damned flex pipe and brace.

Dann

Well I guess I need a second flex pipe lol... And I definitely will be adding a brace as soon as I get it back

I said you need those 2 things because I know you don't have those 2 things.

Shouldn't we be concerned that it's failing through the weld?

thats standard failure mode.

Look at the welds in the photo on the downpipe, they are close to textbook perfect. Abe is clearly very skilled.

He has a flex pipe in the downpipe and the wastegate pipe.

That I do sir

Really, that's weird. Every welding specification I've ever read requires that the material fail in the base metal and not in the weld.

When I worked at Honda we did lots of testing for this exact thing, the tensile specimen was always required to fail in the base metal. If the specimen failed in the weld or in the HAZ then the test was considered a failure.

I don't doubt Abe's skills at all. But in my experience, a failure straight through the weld bead is a big no-no.

the way it split makes me think there's stress there, like the bend needed to open up a bit.

Agreed. I'm no TIG guy but looks like it was just melted together/no filler, and undercut in the process, causing a weak weld.

Then why did it also fail the second weld with a nice fat filler mound there.

This is scary. I've welded a bunch of downpipes with no filler, no reinforcements, no flexes (basically any 'street car' setup i've done), and I'm a far inferior welder to abe, while using inferior material (vibrant bends instead of beautiful steam pipe bends).

SO something's off with the car, not the pipe. What that is, I dunno. :dunno:

How buzzy is your car? Running a chinese flywheel/clutch?

Its not buzzy at all... Smooth actually. Its a FM Stg1 clutch with OEM flywheel. I really dont know what in my car would cause it to keep happening. The downpipe will arrive to Abe on Friday and he will have it headed back in my direction early next week. He is going to be adding a slip joint over the cracked weld to reinforce that joint.

The only thing I noticed when removing the downpipe yesterday was that the exhaust seemed to be pulling down on the back side of the downpipe. I'm assuming that was putting stress on the weld that cracked and thats why it split. I fully plan to add a brace and see what happens this time.

In other news, i'm now a pro at pulling my downpipe. Literally had it out in like 20 mins yesterday compared to 2 hours the first time (Granted, the anti-seize was still fresh on the downpipe hardware)

That shit gets everywhere but it's worth its weight in gold.

I don't know. In one of his pics (this one: http://i119.photobucket.com/albums/o...pszeiucefg.jpg ), it looks like the 2nd weld was not all the way around, there is a spot (that failed) that is still undercut in the pics. Perhaps (again, I don't TIG much so don't know much about TIG) this spot failed and then the crack propegated.

But I dunno. Seems to me something is putting really high stress in that spot. Hence why I recommended a brace.

Random though, but if his EGT's were really high for some reason, would that contribute to this failure?