Re: Re: loosening turbo to mani and turbo to d/p nuts

Thu, 02 Apr 2009 06:43:57 -0700

Inconel would expand even more and cause more of a problem.  The coefficient of thermal expansion for all of the stainless steels (304, 316, 320, inconel, hastalloy, etc.) is nearly double that for the carbon steels.
 
The Mitsubishi world has the same issues, with the added problem of shearing off the endmost studs from the differences in thermal expansion between the aluminum head and cast iron exhaust manifold - the newer cars use a larger stud in the endmost holes.  At one point I was using a belleville ("wavey") washer and wide based locking nuts from BMW to keep things together on an engine that was taxing the max flow of a 16g turbo.  The Belleville washer keeps tension on the joint when the stud expands.
 
Mark


Apr 2, 2009 06:33:29 AM, [email protected] wrote:
I have fought this issue for many years. I have installed bigger studs and
used all manners of locking devices and compounds and nothing has solved
the problem. I can drive on the street for miles and miles with no problems
but a track day brings it right back. I am convinced that the problem is
not with the studs or nuts backing out(because I am sure I prevented that)
but with the studs stretching under the high heat loads seen on track. I
even spoke to ARP about getting some custom studs made from inconel. I
think that would solve the problem but the cost was nuts. My final solution
to this issue was to build a V8 RX7 for track use.

Steve

Things I have tried:

3/8 studs
Safety wire
High temp thread locker - (2000 degrees aircraft shit $$$$)
Nordlocks
Best studs I could find - (ARP header studs)



Emilio -
949Racing
com> MiataPower
Sent by: <[email protected]>
miatapower-bounce cc
[email protected]
Subject
Re: loosening turbo to mani and
04/01/2009 11:39 turbo to d/p nuts
PM









My experience has been that its more the studs backing out. So even, stage
8's, Nordlocks, safety wire and what not doesn't always fix it. Someone at
MRLS mentioned that FM may be switching to or optionally offering 10mm
studs with their kits. The extra surface area does seem to make them stay
put longer. 10m studs have been de rigueur for turbo Miatas that see a lot
of track use but its trickling down to street cars slower it seems. I
haven't tried green, hi temp cylindrical bonding Loctite but that might
help. Another fix might be staking them, but that may raise cracking issues
with cast manifolds.

Jason, you don't track your car do you? That's when stuff falls off :) I've
seen daily driven turbo cars that have never had an an issue on the street,
not make one session at the track before a stud or two backs out.

But to answer your question yes, it's endemic for turbo track miatas.

Emilio Cervantes
www.949Racing.com
26242 Dimension Dr #130
Lake Forest, CA 92630
949.716.3111 phone / fax

On 2009-04-02 03:05, Jason C wrote:
> A lot of people seem to have this problem (though not me)....I want
to understand why some do and some don't. Â Some do despite the
fancy serrated FM washers.Do FM see this problem?



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
_______________________________________________
Miatapower mailing list
[email protected]
http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower


_______________________________________________
Miatapower mailing list
[email protected]
http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
_______________________________________________
Miatapower mailing list
[email protected]
http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower

Reply via email to