Has anyone heard of something call a fire-ring?

I have the aluminum 98mm cylinders with small steps in the top lips. I have been told that they are for fire-rings to allow for expansion of the heads and cylinders when heated. I also believe that they are used on later 964/993 motors, but I am not sure. Can anyone provide me with some info on these? There are more pictures than this one on my website...

More pics of the cylinders...

Take a black marker and "paint" the lower lip so I can use a pointer and 'point' out what your talking about. It doesnt show up in the pics very well.


B

Did you look at any of the other pics on my website...I included a link above.

-Britain

Yes.. and THEN I replied. It doesnt show what we need.


B

Alright, I will do that tomorrow.

For the time being...does anyone else have any idea?

-Britain

Its 11'o clock at night and I asked this question on Pelican over a year ago with the same pics.. nobody knew what the hell I was posting (not even Jakester).



B

Isn't that what they call the extra copper gasket? Like a head gasket, but it goes on the cylinder?

I found out that they are actually called Niresist head seals and used on 964 turbo motors. I also determined that they are typically made out of stainless steel.

-Britain

Nirosist rings

Also used on Hiperf 930s, a groove is cut into the top of the cylinder, and another groove it cut in to the head. then the ring is fit and everything is torqued up, forcing the ring home (its kind of an interference fit). It helps keep compression gasses in the cylinder.