FM Exhaust Brace
02-03-2010, 08:10 AM
#1
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FM Exhaust Brace
What do you guys think of Flyinmiata new exhaust brace. I was hoping a problem for broken studs would come soon as I really want a FM2 hydra and did not want to spend all the money for V-bands. Here is a link for the brace.
Flyin' Miata : Turbochargers : Parts and upgrades : 1999-05 3" FM exhaust brace
Flyin' Miata : Turbochargers : Parts and upgrades : 1999-05 3" FM exhaust brace
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02-03-2010, 12:21 PM
#7
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It's a form of something I've suggest long ago for those running a vertical flanged turbo manifold; two very common miata manifolds come to mind.
I had suggested that adding a small lip on the lower edge of the flange, so the turbo's weight rests on the manifold not the studs, might help the issue.
This brace should help eliminate some pulling forces from below. Just make sure it's after your flex pipe or something like this will happen:
this hole was ripped out of my DP because I tracked it with a brace hold it to the tranny before my flex pipe.
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02-03-2010, 01:27 PM
#9
On the 2.5" NA ones, I would not expect it to fit. On the others, it might work. Maybe.
The intent is to support the turbo from below - or more accurately, take the leverage of the big, long, heavy exhaust system off the turbo. The end result is a happier set of studs. It's been tested on track with excellent success, and it actually seems to cut down on some NVH in the car as well.
We've experimented with having braces welded directly to the downpipe, but they tend to end up like Braineack's picture. You'll notice the factory downpipe brace isn't welded to the pipe, but is clamped around it. The support tears out of the pipe because of the point load on a fairly small area.
Flex joints aren't really a factor, we don't use them in our systems. In fact, putting one of these braces after a flex joint would probably decrease its effectiveness at supporting the turbo.
The intent is to support the turbo from below - or more accurately, take the leverage of the big, long, heavy exhaust system off the turbo. The end result is a happier set of studs. It's been tested on track with excellent success, and it actually seems to cut down on some NVH in the car as well.
We've experimented with having braces welded directly to the downpipe, but they tend to end up like Braineack's picture. You'll notice the factory downpipe brace isn't welded to the pipe, but is clamped around it. The support tears out of the pipe because of the point load on a fairly small area.
Flex joints aren't really a factor, we don't use them in our systems. In fact, putting one of these braces after a flex joint would probably decrease its effectiveness at supporting the turbo.
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02-03-2010, 01:44 PM
#10
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We've experimented with having braces welded directly to the downpipe, but they tend to end up like Braineack's picture. You'll notice the factory downpipe brace isn't welded to the pipe, but is clamped around it. The support tears out of the pipe because of the point load on a fairly small area.
Flex joints aren't really a factor, we don't use them in our systems. In fact, putting one of these braces after a flex joint would probably decrease its effectiveness at supporting the turbo.
Flex joints aren't really a factor, we don't use them in our systems. In fact, putting one of these braces after a flex joint would probably decrease its effectiveness at supporting the turbo.
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02-03-2010, 05:47 PM
#13
I'd like to point out you didn't ask for good pictures.
NA 2.5 installed. This one bolts to the bellhousing and clamps to the downpipe.
NB 2.5 bracket installed, no exhaust clamp (or exhaust) in place. You're looking back from under the engine, the red thing is the PPF. This design clamps on the midpipe just in front of the cat. As long as your downpipe puts the exhaust in the normal location and your exhaust is one of ours it'll fit. This was actually taken on a naturally aspirated car.
NA 2.5 installed. This one bolts to the bellhousing and clamps to the downpipe.
NB 2.5 bracket installed, no exhaust clamp (or exhaust) in place. You're looking back from under the engine, the red thing is the PPF. This design clamps on the midpipe just in front of the cat. As long as your downpipe puts the exhaust in the normal location and your exhaust is one of ours it'll fit. This was actually taken on a naturally aspirated car.
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02-03-2010, 05:52 PM
#14
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I was going to try this exact thing in the summer of 2009, but I decided to give money to Turbo Tim. I hope it works for you gays.
Awwwe, that's a cute little exhaust pipe.
I'd like to point out you didn't ask for good pictures.
NA 2.5 installed. This one bolts to the bellhousing and clamps to the downpipe.
NB 2.5 bracket installed, no exhaust clamp (or exhaust) in place. You're looking back from under the engine, the red thing is the PPF. This design clamps on the midpipe just in front of the cat. As long as your downpipe puts the exhaust in the normal location and your exhaust is one of ours it'll fit. This was actually taken on a naturally aspirated car.
NA 2.5 installed. This one bolts to the bellhousing and clamps to the downpipe.
NB 2.5 bracket installed, no exhaust clamp (or exhaust) in place. You're looking back from under the engine, the red thing is the PPF. This design clamps on the midpipe just in front of the cat. As long as your downpipe puts the exhaust in the normal location and your exhaust is one of ours it'll fit. This was actually taken on a naturally aspirated car.
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02-03-2010, 05:54 PM
#15
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All the broken stud talk had me thinking of a FM2 with a turbotim manifold and downpipe but this will be a lot cheaper and easier to setup so I really hope to hear good feedback
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02-03-2010, 06:09 PM
#16
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I will give my own critique.
I think without a flex joint after the clamp constraint at the bell housing will dramatically increase the stress level at the turbo Joint. I just recently did an FEA analysis of a similar setup on an exhaust for my work I get paid to do. The constraint at the bell housing will serve as a fulcrum for the cantelevered mass of the rest of the exhaust system and it will multiply the bending stress at the turbo joint rather than isolate it from bending stress. Think of it like trying to lever something with a crow bar. The turbo joint is like the tip of the crowbar you can jam the tip of a crowbar in something and try to move it and it wont do much of anything until you give it something to pry against (fulcrum point) so you grab a stick or something and place it back from the tip to lever against and pry away. The constraint at the bell housing becomes the fulcrum in this case. You get bending stress as you go around a corner and the exhaust pipe wants to swing to the side or bounce up and down over bumps or the engine rocks over from torque and the aft part of the exhaust system tries to stay put relative to the engine. It needs a flex section in the system to remove the bending stress you get from the cantilevered mass of the rest of the exhaust system after the turbo. Without a flex coupling your better off not adding a fulcrum.
Also from my personal turbo Miata experience the U-bolt clamp is horrible it never would stay tight. The U-bolt will create too much contact stress and will yield the pipe underneath it and it will constantly need to be retightened as it slowly crushes the pipe creating a ring indention in it, been there done that. The clamp needs to be about a 1” wide strap to avoid crushing the pipe and to keep it tight.
My own personal setup that has worked well after trying several, I still prefer holding it at the bell housing but I have a custom clamp at blousing that has about a 1” wide fabricated clamshell clamp arrangement and a flex joint before the cat. The factory clamp is also creats a wide clamp serfice on the pipe and it works good.
Bob
I think without a flex joint after the clamp constraint at the bell housing will dramatically increase the stress level at the turbo Joint. I just recently did an FEA analysis of a similar setup on an exhaust for my work I get paid to do. The constraint at the bell housing will serve as a fulcrum for the cantelevered mass of the rest of the exhaust system and it will multiply the bending stress at the turbo joint rather than isolate it from bending stress. Think of it like trying to lever something with a crow bar. The turbo joint is like the tip of the crowbar you can jam the tip of a crowbar in something and try to move it and it wont do much of anything until you give it something to pry against (fulcrum point) so you grab a stick or something and place it back from the tip to lever against and pry away. The constraint at the bell housing becomes the fulcrum in this case. You get bending stress as you go around a corner and the exhaust pipe wants to swing to the side or bounce up and down over bumps or the engine rocks over from torque and the aft part of the exhaust system tries to stay put relative to the engine. It needs a flex section in the system to remove the bending stress you get from the cantilevered mass of the rest of the exhaust system after the turbo. Without a flex coupling your better off not adding a fulcrum.
Also from my personal turbo Miata experience the U-bolt clamp is horrible it never would stay tight. The U-bolt will create too much contact stress and will yield the pipe underneath it and it will constantly need to be retightened as it slowly crushes the pipe creating a ring indention in it, been there done that. The clamp needs to be about a 1” wide strap to avoid crushing the pipe and to keep it tight.
My own personal setup that has worked well after trying several, I still prefer holding it at the bell housing but I have a custom clamp at blousing that has about a 1” wide fabricated clamshell clamp arrangement and a flex joint before the cat. The factory clamp is also creats a wide clamp serfice on the pipe and it works good.
Bob
Last edited by bbundy; 02-03-2010 at 06:25 PM.
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02-03-2010, 06:52 PM
#18
Sorry, we lost the files 
Bob, we haven't had any trouble with the clamps loosening. They're not your typical cheap NAPA ones, it could be a matter of fastener quality. I'm not sure this clamp will provide a fulcrum, as it does hold the exhaust into place pretty well without allowing it to rotate. Also, even if it does act like a fulcrum I can't see how that is worse than having the entire exhaust system try to pivot around the turbo.
The factory MSM setup is basically the same as our 2.5 NA design. No flex joints and a solid mount at the bellhousing. Actually, all Miatas come with a similar mount at the bellhousing. We simply weren't able to package it with the other downpipes other than the 2.5 NA.
So far, testing has yielded good results. There are a few more of these on the way to some pretty aggressive Miata drivers who have had stud problems in the past for more data points.
Bob, we haven't had any trouble with the clamps loosening. They're not your typical cheap NAPA ones, it could be a matter of fastener quality. I'm not sure this clamp will provide a fulcrum, as it does hold the exhaust into place pretty well without allowing it to rotate. Also, even if it does act like a fulcrum I can't see how that is worse than having the entire exhaust system try to pivot around the turbo.
The factory MSM setup is basically the same as our 2.5 NA design. No flex joints and a solid mount at the bellhousing. Actually, all Miatas come with a similar mount at the bellhousing. We simply weren't able to package it with the other downpipes other than the 2.5 NA.
So far, testing has yielded good results. There are a few more of these on the way to some pretty aggressive Miata drivers who have had stud problems in the past for more data points.
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