Cylinder sealing is affected by each component in the cylinder kit. The piston and rings are of course major players in achieving optimal cylinder sealing, along with cylinder bore geometry and honing finish.
For this discussion, we will be concentrating on the influence the piston and ring groove has to cylinder sealing in high performance applications.
Blow-by gas leakage past piston rings will follow the path of least resistance and without preference. It is often assumed that if an engine has excessive blow-by, the gas leakage is predominately occurring between the outside peripheral surface of the ring and the cylinder bore.