Yes i built the rb25/30 , that i sold to Skit . I used the stock rb25de pistons on the rb30e rods . Edge of pistons were sitting 1.2 mm below top edge of block , that was supposed to be good for 10.5 -1 compression , but i have recalculated that because head gasket thickness wasnt allowed for before . Also the rb25de pistons sit above the edge of the block , i measured .5 mm , just as well the head gasket is around 1 mm thick . So i figure the compression to be around 9.8-1
I,m now building another rb25/30 , again using rb25de pistons on the rb30e rods . This time the block is being decked 1.2 mm to bring edge of pistons flush with top of block at tdc . I dont want the pistons sitting above the deck like they do in rb25de . i calculate the compression to be 11.0-1 with this set up .