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Old 12-04-2020, 05:04 PM   #1
Jussi Alanko
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Default Studs to turbine housing?

Ok, i bought a Holset hx40 super while ago, it's in very good condition except studs for the downpipe flange.

They were in bad shape, and threads at the studs was almost all gone. So i decide to change the studs. They were extreme hard to get out at the turbine housing, almost all of the six studs snaps off and i had to weld big nuts to broken studs, i get five of six out this way, but one is so hard to get out that i had to drill a 6.5mm hole at center of the remaining stud and turn a new m8 thread to existing hole where remaining stud was.

operation goes ok, and now i had a turbine housing with good threads.

However i'm gonna sell this 18cm housing and buy a new 16cm housing.

When i get this new housing, which kind of studs i had to put in it? They need to be hard enough that threads remains in good condition, i will use a copper locking nuts to it.

Tonight i'm looking different kind of studs at ebay, where they are cheap. I even consider to put a titanium studs to it, another good option is 12.9 rated hardened steel studs.

When i install the downpipe flange i use a copper paste to the studs and for the nuts.

My goal is that i can remove and install downpipe many times without breaking the studs, it's actually must to remove and install flange again and again, when i duild downpipe and rest of the exhaust system.

I'm considering to use a v-band flange adapter to turbo, but it cost about 90€, it looks like that:



It solves most of the problem of bad studs, because they need to tighten just once. But still i want that they will be in good shape after years of use, and when time comes to remove downpipe they must be easily loosen out.

So, which studs i buy, normal steel, hardened steel, rst or titanium. In any case i will use copper nuts and a copper paste?
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Old 12-04-2020, 06:42 PM   #2
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Not sure what your question is. If you are asking about stud type, a 10.9 grade stud with copper paste and a copper coated locknut should be plenty. If you are worried about it backing out, you can use Nord Lock washers.
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My knob has a big chunk of steel on it
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Old 12-04-2020, 06:52 PM   #3
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inconel studs or bust
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Old 12-04-2020, 06:56 PM   #4
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inconel studs or bust
Link or GTFO.
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Old 12-04-2020, 07:24 PM   #5
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Link or GTFO.
Yes. I have spent hours trying to find Inconel studs. M10 x 1.5 specifically. RX7 studs are alleged to be Inconel.
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Old 12-04-2020, 07:33 PM   #6
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The 90+ exhaust studs from volvo aren't steel...
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Old 12-04-2020, 11:47 PM   #7
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The OEM Volvo studs that are inco have an N stamped in the end. They are all M8 AFAIK.
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Old 12-05-2020, 12:53 PM   #8
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Originally Posted by arsenix View Post
The OEM Volvo studs that are inco have an N stamped in the end. They are all M8 AFAIK.
Where i can buy these studs, and what are their dimensions?
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Old 12-05-2020, 01:05 PM   #9
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Is it a good idea to buy a marine grade stainless studs+copper lock nuts?
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Old 12-05-2020, 01:44 PM   #10
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Quote:
Originally Posted by arsenix View Post
The OEM Volvo studs that are inco have an N stamped in the end. They are all M8 AFAIK.


the good stuff.
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Old 12-06-2020, 05:20 PM   #11
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the good stuff.
And if someone wants the Volvo studs in M10, the B204FT/GT engines use M10 hardware on the mani-turbo connection.
Not sure how easy those can be sourced though.
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Old 12-07-2020, 10:30 AM   #12
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Originally Posted by Jussi Alanko View Post
Is it a good idea to buy a marine grade stainless studs+copper lock nuts?
321 stainless is a good choice for high temp applications. Much stronger than your basic 304/ 18-8
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Old 12-07-2020, 12:31 PM   #13
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Quote:
Originally Posted by arsenix View Post
The OEM Volvo studs that are inco have an N stamped in the end. They are all M8 AFAIK.
Learn something new every day

I had to go look in my stash - I don't discard studs I remove if they are in good shape.

All the exhaust manifold studs I have (white block, no shoulder) are stamped E

Some shouldered studs are marked N, and others G



I wouldn't assume a SS stud is 'better' - I'm pretty sure the material properties may be too brittle in some applications - I'm sure Ben is more knowledgeable on the topic of material properties to speak to that. (EDIT just saw his last poset RE: 321 SS)
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Old 12-07-2020, 12:45 PM   #14
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FWIK, Stainless isn't ideal for a few reasons, 2 of them being

1) galvanic corrosion in an aluminum head
2) greater thermal expansion (leads to fasteners loosening)

If you are using it in a manifold... especially a SS manifold. its a better match. Probably would live fine in a cast iron manifold too.
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Old 12-07-2020, 01:41 PM   #15
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You might try to find some BUMAX 88 fasteners. its a SS grade specifically made for fasteners.

its much more fatigue resistant than standard grade SS fasteners.
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Old 12-07-2020, 02:08 PM   #16
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Inconel 718 would probably be the best available option but overkill for the turbine outlet / downpipe application.

Next best choice is probably A286 which is an iron-based superalloy. See if you can find A286 studs in M8 and use copper antiseize on the nut end. That should be super reliable.
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Old 12-08-2020, 04:24 PM   #17
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Lookielook:

https://folkraceshop.se/volvo/insug-volvo
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Old 12-09-2020, 07:34 AM   #18
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I bought a stainless studs and a copper nuts, and i use an antiseize copper grease when i install those.
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