Artech Downpipe crack. Will a repair hold up? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-16-2015, 01:10 PM   #21
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Yep pulling the downpipe out tomorrow and bringing it to be repaired. I will get the clamp on this weekend
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Old 03-16-2015, 01:11 PM   #22
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Check out my build thread for the brace I started. I'm going to try and finish it today or tomorrow.
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Old 03-16-2015, 01:31 PM   #23
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Check out my build thread for the brace I started. I'm going to try and finish it today or tomorrow.
Nice thanks! Subbed
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Old 03-17-2015, 06:12 PM   #24
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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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Old 03-17-2015, 06:15 PM   #25
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Old 03-17-2015, 08:13 PM   #26
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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.

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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
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Artech Downpipe crack. Will a repair hold up?-20150317_142021_zpsqaqiry2x.jpg   Artech Downpipe crack. Will a repair hold up?-20150317_142030_zpsd6geol7f.jpg   Artech Downpipe crack. Will a repair hold up?-20150317_142049_zpsfbyue8wj.jpg  
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Old 03-17-2015, 10:40 PM   #27
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I dailied a turbo miata for YEARS.

Misfire, first thing new plugs. 1/2 the time that fixes it for me.
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Old 03-17-2015, 11:07 PM   #28
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Originally Posted by patsmx5 View Post
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
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Old 03-17-2015, 11:11 PM   #29
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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.
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Old 03-18-2015, 03:49 AM   #30
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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 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.
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Old 03-18-2015, 06:18 PM   #31
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Awesome fix and price for the repair!

OTOH, I can't believe I gave Abe his first prop!
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Old 03-18-2015, 06:27 PM   #32
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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

Heh, just yankin' your chain Abe, I love my ARTech goodies. Nicest thing in my car by fair margin.
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Old 03-18-2015, 07:44 PM   #33
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Quote:
Originally Posted by patsmx5 View Post
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.
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
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Old 04-06-2015, 08:46 AM   #34
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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 **** 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...

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Old 04-06-2015, 08:52 AM   #35
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there has to be stress on that pipe once installed, then once it expands in heat, it's too rigid and snaps.
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Old 04-06-2015, 08:55 AM   #36
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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.
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Old 04-06-2015, 11:47 AM   #37
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I'd suggest gussets, like turbotim did. Something like 1/8 or even 1/4" diamonds of material welded across the stress point.



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.
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Old 04-06-2015, 11:57 AM   #38
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Quote:
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I'd suggest gussets, like turbotim did. Something like 1/8 or even 1/4" diamonds of material welded across the stress point.



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.
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Old 04-06-2015, 12:27 PM   #39
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Quote:
Originally Posted by nitrodann View Post
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")
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Originally Posted by patsmx5 View Post
Yeap. Do this, and reweld the weld that's cracked.
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Originally Posted by shuiend View Post
I would reweld, then work on a transmission brace.
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.
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Old 04-06-2015, 12:35 PM   #40
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Quote:
Originally Posted by patsmx5 View Post
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.
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