IAG Performance Stage 3 Magnum EJ25 Closed Deck Case - 14mm H.S.M. Fire-Lock, (No Bore & Hone)

IAG's Stage 3 Magnum Closed Deck converted case halves were created to be the most affordable and cost-effective short block modification for EJ25 Subaru turbo engines. IAG machines the case halves assembled together in our Haas VF-4SS CNC mill to accept the IAG CLOSED Deck Inserts that transform the block into a solid deck. The unique inserts feature small passages that allow needed coolant flow to the deck surface. The case halves are then CNC machined for our new Fire-Lock head gasket solution that is loosely derived from diesel technology where a counterbore step is machined around each cylinder bore allowing specially sized fire rings to drop into the machined area and head gasket bores. The Magnum case is then drilled and tapped to accept 14mm head studs that combined with the IAG Fire-Lock head gasket set greatly reduces head gasket failure during high cylinder pressure scenarios. The OEM Subaru EJ25 case is referred to as a semi-open (or semi-closed) deck. The block is essentially an open deck with 3 narrow supports tying in the main case to the tops of the sleeves. This feature was a slight improvement over the previous open deck EJ20 cases. The purpose of the deck supports is to keep the sleeve from moving. While conceptually this is an improvement, the reality is that it simply isn't enough for a high horsepower Subaru. The weakest point of the sleeve is still left open and unaddressed.