Sealing and big-bore setups

[Edwin Ek]

In the old days, 86mm bores seemed to be the maximum before sealing problems started to appear. However, nowadays bores up to 91mm have become common.

Has something changed or been improved, or is sealing still problematic but not discussed much?

[John Brooks]

Computers are the change

[Vic Skirmants]

Computers are the change

????
Any bore larger than 86mm requires machining the head for larger OD cylinders. You're NOT getting 86s into a standard OD cylinder.
John; what are you talking about?

[Ron LaDow]

In the old days, 86mm bores seemed to be the maximum before sealing problems started to appear. However, nowadays bores up to 91mm have become common.
Has something changed or been improved, or is sealing still problematic but not discussed much?

Are you concerned with the ring/cyl seal or the head/cyl seal?

[John Brooks]

Vic, Ron,

I was trying to refer to the tighter tolerances attainable through CNC machining of the newer parts and reworking older components. The last set of new Rods and Pistons I ran across the scales were perfect, not a milagram difference. The newer computer controls allow for better finish and repeatability