Whats better? Cast manifold inconel or welded steel vband
04-11-2011, 05:01 PM
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Whats better? Cast manifold inconel or welded steel vband
I'm tired of my stud stretch problem, I am currently using a begi cast manifold with stage 8 hardware and a downpipe brace to the transmission, I went from 20 minutes on track failing to about 3 days before failure, but its still failing...
I've searched and see two successful solutions, which is better?
Proven cast manifold with inconel studs?
Expensive v band manifold along with new exhaust housing?
Thanks in advance, looking for first hand experiences with either setup, or better yet someone who's tried both. On track.
Don
I've searched and see two successful solutions, which is better?
Proven cast manifold with inconel studs?
Expensive v band manifold along with new exhaust housing?
Thanks in advance, looking for first hand experiences with either setup, or better yet someone who's tried both. On track.
Don
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04-11-2011, 05:06 PM
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If you are building a tubular-based setup from scratch, the v-bands are a great option, but the Inconel studs are just as effective.
In-stock, ready to ship.
http://trackspeedengineering.com/sto...-kit-p-98.html
In-stock, ready to ship.
http://trackspeedengineering.com/sto...-kit-p-98.html
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04-11-2011, 05:13 PM
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Is it gauranteed for any length of time? 
If it were easier to work on i'd almost be willing to just deal with re tightening. But seriously what's the longest confirmed amount of testing the inconel studs have been subject to?
If it were easier to work on i'd almost be willing to just deal with re tightening. But seriously what's the longest confirmed amount of testing the inconel studs have been subject to?
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04-11-2011, 05:23 PM
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Sav - going to do one track day with the setup as-is and I suspect after it I'll be wanting to upgrade to your Inconel stuff.
My turbo uses 8mm studs though. Can any old machine shop drill and tap the manifold for the larger 10mm stud as well as drill out the holes in the turbo, or is that a specialty job?
My turbo uses 8mm studs though. Can any old machine shop drill and tap the manifold for the larger 10mm stud as well as drill out the holes in the turbo, or is that a specialty job?
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04-11-2011, 05:35 PM
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Sav - if you want to sell these as an upgrade to 8mm stud users, if you can send a nut/lock washer from that kit I can see if they will clear the compressor housing. Or, if you have a nut/lock washer at Buttonwillow on the 17th, maybe then.
-Ryan
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04-11-2011, 06:05 PM
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The nature of this failure is such that it usually happens fairly quickly - a mild/stainless stud gets overheated, loses its tensile/yield strength, and creeps. It's a noncatastrophic tensile failure, not a fatigue failure, so the problem we aim to solve with the Inconel studs doesn't have a significant time factor associated with it. The Inconel won't lose its yield strength at the same temperature, so it won't creep - simple as that. I'm sure the material has some sort of fatigue cycle limit, but it's not something that we could reasonably be expected to test since it could take thousands and thousands of hours to induce. It's comparable to assembling a turbo downpipe with nylon hardware, and then changing it out for steel - not quite as dramatic, but it's the same idea. You're switching to a material that is designed for the stresses and strains of the environment (inco), vs. one that is known to fail in the same environment (steel).
As far as we know, the 10mm hardware and Stage8 nuts will fit any Garrett T25 .64 A/R or larger exhaust housing (aka standard GT2554R/GT2560R housings). Sonny's car is a GT2560R.
Ryan, I'll throw a kit in the truck this week so you can take a look at BW this weekend.
If someone wants to tell me exactly how much clearance there is from the stud center to the first interference point on the turbo flange, I can tell you whether it'll be possible to fit the 10mm stud. We have to have these produced in pretty large quantity to offer them at that price, so there's virtually no chance of ever seeing an 8mm version of this product. Having said that, if there's significant interest in an 8mm version, we could organize the group buy and have them made. We'd have no way to test them and no ability to offer refunds if they fail, however, which is why it's something we've never seriously explored.
FYI - our upcoming turbo kits will have these studs as standard equipment. In our view, they are an absolutely required addition to any turbocharged Miata that sees track duty.
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04-11-2011, 07:04 PM
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Ok, out of curiosity. If you were to do the work, tap my manifold to accept the new studs, install the turbo with your hardware including new bolts etc, would you gaurantee it for any period of time, or number of events? If so how much? I'm in the northern bay area, I almost exclusively do all my own work but I'd love to "buy" a solution to this problem.
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04-11-2011, 08:15 PM
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I think our longest test subject is VagaXT's MSM. I can't give an exact life for them since we've never had one stretch. The nature of this failure is such that it usually happens fairly quickly - a mild/stainless stud gets overheated, loses its tensile/yield strength, and creeps. It's a noncatastrophic tensile failure, not a fatigue failure, so the problem we aim to solve with the Inconel studs doesn't have a significant time factor associated with it. The Inconel won't lose its yield strength at the same temperature, so it won't creep - simple as that. I'm sure the material has some sort of fatigue cycle limit, but it's not something that we could reasonably be expected to test since it could take thousands and thousands of hours to induce.
The nature of this failure is such that it usually happens fairly quickly - a mild/stainless stud gets overheated, loses its tensile/yield strength, and creeps. It's a noncatastrophic tensile failure, not a fatigue failure, so the problem we aim to solve with the Inconel studs doesn't have a significant time factor associated with it. The Inconel won't lose its yield strength at the same temperature, so it won't creep - simple as that. I'm sure the material has some sort of fatigue cycle limit, but it's not something that we could reasonably be expected to test since it could take thousands and thousands of hours to induce.So yes, inconel really is magic.
EDIT: The coefficients of thermal expansion really aren't that different (7.0 vs. 7.3 microinch/F), it's just the stress imparted by the more rapidly expanding turbine housing.
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