I don’t have a lot to add too any of the comments. .005” bore taper is kind of my max that I will consider a rering. More than .005” across all holes or higher it needs bored. With .003” to .005” hold the RPMs to 5000, 5500 max. When he have tried too turn engines with that much bore taper past 5500, via bigger cam or better heads…we pretty much always made them slower. Under boost we pushed past that, I think the turbo compensated. NA with bore taper hurts top end power.
I have had more issues from freshly bore engines with new oversized pistons (and not bore with a tq plate) than a rering OEM seasoned engine.
On a low compression engine for a rering I will use moly rings. On high compression pump gas we prefer too use a cast type ring, like mentioned in that post Mike did in post 3. Or something that is both resilient and can take heat on the top ring, and a moly ring on the second. Best of both then. The cast hold up better with extra heat (like preignition) than the moly. We have had trouble with the moly rings loosing there tension more than cast rings. I have peeled some off the piston like a piece of wire. The moly rings on the top ring, can seem to work harden quicker if it is a high compression engine with bore taper. The bore taper is always the worst at the top of the cylinder were the top ring seats.
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