Rick,
I have seen this type of metallic o-ring used in the Nissan turbo cars. I
have also seen a similar metallic o-ring that was not pressure filled with
nitrogen but was ported with tiny holes on the interior of the ring. When
placed in the step bore at the top of the cylinder the exhaust gases would
pressurize the o-ring How effective is this compared to the nitrogen filled
rings? They are a litter cheaper.
Jim Bickford
----- Original Message -----
From: "Rick Byrnes" <rick@rbmotorsports.com>
To: <DaCudaKid@aol.com>
Cc: <land-speed@autox.team.net>
Sent: Saturday, March 17, 2001 6:25 AM
Subject: Re: Head Gaskets
> Hi Mike
>
> Metallic "O" rings are not new, they just seem like a closely guarded
> secret.
> Made from .062" dia, .010" wall Inconnel X 750 tubing, formed into a hoop
> and then welded and ground at the weld. During the manufacturing process
> they fill with a high pressure gas Nitrogen I think. A company called
> Helico Flex, in S. C. produces them in lots of sizes, but actually makes
> them to my (or your) specification. They are expensive. When ordering 25
> or more the price is/was $24 each. These type of parts are used to seal
> very high pressure steam at Nuclear plants and are very well engineered.
> The O ring sets in a step in the bore rather than a groove. With big
bores
> there just isn't room so a counterbore does just fine.
> The logic, behind the design is the metal O ring provides a very high unit
> load to seal high pressure combustion gas, and as temperatures increase
and
> the properties of the metal decline, the high pressure gas has expanded
and
> supports the original sealing (unit load). They work well, and of course
> provide a metal/metal clamping joint that is much more stable than the
> typical gasketed joint. If you flow water and oil thru this joint you
still
> need elastomer O rings at each location. If anyone is interested in
> specifics, I can take some photos and post. (Glenys just got a new digital
> camera).
> Even for us crazys, most of us don't need this kind of approach to
sealing.
> Roush used this in the 2.5L GTO motors they used in the 80's and never had
a
> problem. What was interesting about that program is they never had any
type
> of engine failure in public. Except one pilot burning down one engine
when
> he lost coolant after a shunt. He didn't DNF though....
> I was very fortunate that late in the program Lee White, then the manager
of
> the GTO program shared some of the non propriority items with me. I'm not
> too proud to copy.....especially the good ones.....
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