EPIC nuts/studs loosening thread (reposting stupid stuff without reading = warning)
03-31-2010, 02:21 AM
#1021
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Agreed, I don't change mine that often. What I'm getting at is if you have a solution you know will last 5 track days, and you replace it every session or every other, you're golden - yes you're throwing away hardware with a few more track days in it, but it's a reasonable solution.
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03-31-2010, 10:42 AM
#1024
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These actually lasted 5 full track days with my setup. But yes with a stock BEGI cast log I was lucky to get more than one 20 minute track sessions without the turbo wanting to fall off I have lots of experiance with that.
Bob
Bob
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03-31-2010, 02:27 PM
#1030
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Bob
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03-31-2010, 03:00 PM
#1032
Most certainly I did. :-)
Interestingly, the "new" (there's always a new FM design) FM design has no studs exposed to the gas flow (I had Jeremy check).
Last night I was thinking about this - I'm sure it's been asked here - why are there no cast iron studs? Certainly that would help with most of the CTE issues.
Really, the actual answer has been posted a couple times - it requires swallowing your pride and tapping for an english thread, and using the right CTE studs.
I'll probably end up getting one of those new FM manis to replace my old one, and I'll certainly tap it for 10mm. I'm a bit worried it'll blow out into the gas if I do. :-(
I had been using low grade 8.8 studs but 10mm in my current setup. I think some of the minor detail differences between my manifold and stud setup from the standard Begi/FM geometry made it significantly better than those setups. Didn’t seem to matter what I used in the cast log everything failed fairly quickly with hard track use. I am hoping using higher strength 10.9 studs will make my current setup a bid better yet.
Bob
Bob
Last night I was thinking about this - I'm sure it's been asked here - why are there no cast iron studs? Certainly that would help with most of the CTE issues.
Really, the actual answer has been posted a couple times - it requires swallowing your pride and tapping for an english thread, and using the right CTE studs.
I'll probably end up getting one of those new FM manis to replace my old one, and I'll certainly tap it for 10mm. I'm a bit worried it'll blow out into the gas if I do. :-(
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03-31-2010, 03:06 PM
#1033
Here's a quick cheatsheet on this subject, as I see it:
1. DO use a v-band manifold/turbo
2. If you can't swing the cash for #1, DO use a manifold that does not expose the studs directly to the exhaust gas in the manifold
3. If you ignore #1 and #2, DO use the most heat-tolerant studs you can find / afford. Inconel studs are best. Class 12.9 is next. Class 10.9 is after that. However, the non-inco stuff still won't cut it long term. In any case, DO NOT use the cheapest Harbor Freight studs you can find.
4. DO use a hanger (see above) or block-mounted brace to support your turbo. This will lighten the load on the studs (and manifold)
5. Locking hardware of various sorts doesn't really address the root problem of HEAT causing relaxation at the stud/manifold interface, which is a function of the material properties of the stud size and material, and the manifold material
6. Use the largest diameter stud you can package. 10mm > 8mm.
1. DO use a v-band manifold/turbo
2. If you can't swing the cash for #1, DO use a manifold that does not expose the studs directly to the exhaust gas in the manifold
3. If you ignore #1 and #2, DO use the most heat-tolerant studs you can find / afford. Inconel studs are best. Class 12.9 is next. Class 10.9 is after that. However, the non-inco stuff still won't cut it long term. In any case, DO NOT use the cheapest Harbor Freight studs you can find.
4. DO use a hanger (see above) or block-mounted brace to support your turbo. This will lighten the load on the studs (and manifold)
5. Locking hardware of various sorts doesn't really address the root problem of HEAT causing relaxation at the stud/manifold interface, which is a function of the material properties of the stud size and material, and the manifold material
6. Use the largest diameter stud you can package. 10mm > 8mm.
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03-31-2010, 05:03 PM
#1034
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Most certainly I did. :-)
Interestingly, the "new" (there's always a new FM design) FM design has no studs exposed to the gas flow (I had Jeremy check).
Last night I was thinking about this - I'm sure it's been asked here - why are there no cast iron studs? Certainly that would help with most of the CTE issues.
Really, the actual answer has been posted a couple times - it requires swallowing your pride and tapping for an english thread, and using the right CTE studs.
I'll probably end up getting one of those new FM manis to replace my old one, and I'll certainly tap it for 10mm. I'm a bit worried it'll blow out into the gas if I do. :-(
Interestingly, the "new" (there's always a new FM design) FM design has no studs exposed to the gas flow (I had Jeremy check).
Last night I was thinking about this - I'm sure it's been asked here - why are there no cast iron studs? Certainly that would help with most of the CTE issues.
Really, the actual answer has been posted a couple times - it requires swallowing your pride and tapping for an english thread, and using the right CTE studs.
I'll probably end up getting one of those new FM manis to replace my old one, and I'll certainly tap it for 10mm. I'm a bit worried it'll blow out into the gas if I do. :-(
I don’t think we fully understand the CTE issue. Cast Iron already has a lower CTE than any of the stud materials. If everything was heated evenly the studs should expand more and reduce clamp load a tad but not stretch. The CTE problem seems to be a transient thing where not all parts in the are at close enough to the same temperature and there is large temperature gradients occurring. Sudden On off load, temperature spikes, or rapid temperature changes propagating through the parts as seen only on Miatas getting the **** driven out of them on a track seems to be the issue.
Bob
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03-31-2010, 06:26 PM
#1036
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Like Huster said, how many more times must I post this pic? 
I'm doing a 'version 2' this weekend that's even less loggy...or more "directed pulse".
Shameless plug. There's a tubular absurdflow manifold that'll directly replace the BEGI piece and has none of the flange holes into the "stream". Through bolts are possible too. Pic below of the first and only (hit refresh or F5 if no pic shows). It's NOT a log mani damnit.
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04-01-2010, 01:38 PM
#1039
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Do you run a gasket between mani and turbo, Splitime?
This is probably completely misguided, and I'll probably be proven wrong in short order, but I just thought of a little theory that I'll run by you engineer types.
So, people say that it's not just vibration which loosens nuts, but also the thermal expansion of the metal. So, in a gasketless connection, there is nothing to compress so the metal simply grows and pushes the nut loose. With a gasket, there's something to compress and the nuts stay put.
Be gentle guys.
This is probably completely misguided, and I'll probably be proven wrong in short order, but I just thought of a little theory that I'll run by you engineer types.
So, people say that it's not just vibration which loosens nuts, but also the thermal expansion of the metal. So, in a gasketless connection, there is nothing to compress so the metal simply grows and pushes the nut loose. With a gasket, there's something to compress and the nuts stay put.
Be gentle guys.
Both times it resulted in total destruction of the turbo when the gasket barbequed due to a leak broke apart then got sucked through the turbine chewing up the turbine blades on its way through. Basically destroyed two turbo that way. There are definitely conditions where the turbo is sucking a vacuum on the exhaust manifold when you are driving the **** out of it on the track those broken gaskets were sucked in not blown out.
Bob
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