IAG Performance S3M EJ25 Case Half Set Stage 3 Magnum EJ25 Closed Deck Case - 14mm H.S.M. Fire-Lock, (No Bore & Hone)

Subaru: Forester 04 - 13 XT Premium / XT / XT Limited, Subaru: Legacy 05 - 09 GT spec.B / GT, Subaru: WRX STI 15 - 21, Subaru: Impreza 02 - 14 WRX STI / WRX

• Attention: Special note about using ARP Case Bolts - IAG recommends line honing the case when using ARP Case Bolts to remove any distortion created by the hardware. IAG installs ARP CASE BOLTS with 30W engine oil using OEM SUBARU torque specs and procedures. Other torque specs and lubricants may lead to case distortion damage.
• Bore and hone additional and required before final assembly!
• Case Includes: (x1) IAG Stage 3 Magnum Closed Deck converted EJ25 Case Halves (Starts with brand new OEM case), Machined for 14mm Head Stud Conversion (14mm Head Studs sold separately), IAG Fire-Lock receiver groove machining
• IAG Fire-Lock head gaskets REQUIRED PN# IAG-ENG-1740
• If using on 2002-05 Subaru EJ20 2.0L WRX additional modifications and parts are required.
• The block is then placed into a block oven at a low temperature. Our pre-machined closed-deck inserts are simultaneously chilled using dry ice. When the case and inserts have reached our desired temperature, they are moved into our install station, which holds the block and lightly presses the inserts into position on one side of the deck surface. This process is repeated on the other side and then the partially completed case is moved to a cooling rack. In the next step of our process, the case is loaded and fixtured back into the VF-4SS after reaching room temperature. During this stage, the flanges left from machining the inserts are milled close to the case deck surface. Features such as coolant passages and case bolt access positions are machined in preparation for the final stages of our conversion process. Each deck surface is then machined true and flat using a Poly Crystal Diamond insert.
• The IAG Closed Deck starts with a new OEM EJ25 bare case. The case is loaded and fixtured to a 4th axis rotary indexer in our 2015 Haas VF-4SS CNC Vertical Machining Center. It is supported by the main journals using a precision ground 2-inch bar and tailstock which ensures the datum is the main journals. This method gives us a true reference point to perform all machining operations. A Rennishaw probe is utilized to check that the case is fixtured true and once confirmed the machining process begins. Once the case is fixtured, the first step is to mill out 12 pockets for CNC inserts. Rather than attempting to install inserts into an inconsistent cast case, the pockets are milled out to exact dimensions creating a consistent area that accepts our precision inserts. Once the pockets are machined, the case is removed from the mill.

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.