86mm, thats pretty damn big for an LS block. I didnt think you could do that unless you resleve the block and you would have to have the domes on the ITR head recut to fit the larger pistons or else you the domes will be to small if im not mistaken. I thought the B20z had different cylinder sleves than the other b-series engines that allowed them to have the large pistons in them. The b16a and b18c both have 81 mm bores dont they?