Rb 26 piston to wall clearance

Hi all. I am currently having an rb26 bottom end put together. Power goals are 800+ hp on e85. I have new cp 86.5 mm pistons and the bore is a little big. The piston to wall clearance is .007" and the spec sheet calls for .0035.

My understanding is cp lists the minimum ptw clearance on the spec sheet. I know .007 is big. If we coated the skirts to get us closer to .005 would we be ok?

Thanks for the input!

I assume this is a case of buying the pistons before learning the bores were already oversize, and badly worn, rather than a botched hone?

I wouldn't consider anything other than buying new 87.0mm pistons and boring and honing to the correct P2W clearance, and selling the 86.5mm pistons - might get a trade-in discount?

That way you will have known round, and correctly clearanced, bores - I say "round", because if the bores are worn, they AREN'T round!

If you really want to use the pistons you have, you're looking at the cost of the "coating" - and some are more applicable than others, and still looking at a potentially noisy, oil-burning engine with excessive blow-by.

I never dealt with RB engine but have a lot of experience with JZ and 4g engines. The safest builds 1000+ hp we ever had that never gave us any sort of trouble with pistons of many different brands were made with piston to wall clearance 0.012-0.013 mm which is about 0.005 inch. 0.007 is too big whilst 0.004-0.005 works just fine with highly loaded cylinders ( over 150hp per cylinder).

However, if your power goal isn't that high i would go to the next size pistons and make ptw clearance smaller ( budget permitting)...