Pistons QSC 2,7

[Henry Schmidt]

If this is a CE ring , it's broken and should not be installed. If it's an after market attempt to replace a CE ring it seems lame to design it with a split.
Many years ago, Bob at CMW tried installing a stainless wire (with a tiny end gap for expansion) that sat a little proud of the groove as an option to CE rings but if I remember correctly, that didn't yield very good results.
As for piston ring installation: In air cooled horizontally opposed engine, the ring gaps should be staggered at 120 degree intervals. Set all the ring gaps in a line is a sure way to create a transfer path.
Rings are designed to rotate in the ring groove during operation so after the engine runs for a few 100 hrs the gaps could be anywhere.

[HawgRyder]

A long time ago I saw a different type of sealing ring.
It was a hollow stainless steel tube pressurized with an inert gas I think...and it allowed itself to crush slightly in order to seal.
I can't remember the application.
I wonder if something like that would be better in sealing because it would allow for slight deviations in the surfaces and still seal.
Bob

[Lapkritis]

Originally Posted by Henry Schmidt

If this is a CE ring , it's broken and should not be installed. If it's an after market attempt to replace a CE ring it seems lame to design it with a split.
Many years ago, Bob at CMW tried installing a stainless wire (with a tiny end gap for expansion) that sat a little proud of the groove as an option to CE rings but if I remember correctly, that didn't yield very good results.
As for piston ring installation: In air cooled horizontally opposed engine, the ring gaps should be staggered at 120 degree intervals. Set all the ring gaps in a line is a sure way to create a transfer path.
Rings are designed to rotate in the ring groove during operation so after the engine runs for a few 100 hrs the gaps could be anywhere.

Yep, all in agreement for once. Mark the date! I could see how it sounds like I intended for all piston ring gaps to be at 12 o'clock which is not what I intended. I would avoid 6 o'clock for any ring on a horizontal cylinder as a best practice during assembly. If they move about eventually with vibration then that's fine. We follow the same rules with staggering ring gaps in non-Porsche engines such as v6 and v8 configurations. If you use a split head sealing ring on those engines you put the split to the top and nearest a fastener to prevent weeping when relaxed. You file the ends of the wire square and to fit.

The stainless wire requires a surface to bite into such as a gasket. The protrusion of the wire must be specific ratio to the thickness of the gasket to function properly. There are a few, as I'm sure you're aware, that also channel the head and locate onto the same wire that is channeled into the cylinder surface. I wouldn't recommend stainless wire ring into direct contact with the 911 head without re-designing for a sandwich gasket of copper and a ring on either side staggered in size... and I would adhesive sealant the whole party. If the OP has access to the machines then he could probably take it that far and adjust the deck height difference out.

[crummasel]

Originally Posted by Henry Schmidt

Interesting approach, Henry. I know from other engine builds (non-Porsche) i made, this works perfectly well.

Where do you source such rings (or are they own-made?)

Meanwhile i got another project besides of the "housewives project" where 92 QSC were requested for a mildly improved 2,7 165HP US non-catalyst car as a cruiser. The guy agrees to be the guineapig and wants it and its me to have to make the best out of it.