Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec Piston durability

You've misunderstood the issue.

The ring is a little closer to the combustion, but it isn't the rings that are breaking, it is the metal support, the ring land for the rings that is cracking.
Typically in cases where there is no melting of the aluminum present, the support for the lower compression ring is the part that is breaking. This particular support is half the thickness on the mid 99 and earlier pistons. In late 99 and up, this area was doubled in thickness by shifting the two rings upward by a couple of milimeters.
This is why under whatever loads and/or detonation that are breaking the lands is more prevalent on the earlier pistons.

As far as the two front bank pistons going out, they are the two that are furthest from the TB.