IAG 1150 2.5L Subaru Closed Deck Short Block For WRX, STI, LGT, FXT - 1150 BHP

IAG 1150 2.5L Subaru Closed Deck Short Block – WRX, STI, LGT, FXT | 1150 BHP

Part Number: IAG-ENG-S115  |  Power Rating: 1150 BHP  |  

The IAG 1150 Closed Deck Short Block is IAG's most extreme EJ25 foundation — purpose-built for competition drag racing and high-horsepower street builds. Every unit is assembled from 100% new components and machined in-house on Haas VF-4SS CNC mills and a Sunnen SV-30 cylinder hone to exacting tolerances.

Stage 4 Closed Decking eliminates the structural weakness of the OEM open deck, with IAG's proprietary inserts pressed in via a liquid nitrogen/oven thermal process and machined to a mirror finish. Coolant passages are retained within the inserts — no overheating risk, even in daily-driven applications.

The IAG Fire-Lock™ head gasket system — derived from diesel counterbore technology — machines a receiver groove around each bore to accept fire rings, paired with 14mm ARP head studs, nuts, and washers. This system is the definitive solution to head gasket failure under extreme boost. Note: IAG Fire-Lock™ head gaskets (PN# IAG-ENG-1740) are required and sold separately.

The bottom end is built around an IAG-Spec Billet Crankshaft matched to ACL or King race main bearings, IAG Tri-Beam +2mm forged connecting rods with ARP 625+ rod bolts, and IAG-Spec JE FSR 99.75mm 2618 forged pistons with electroless nickel plated tops, H13 tool steel wrist pins, gas ports for ring sealing under high boost, and a 25% larger oil ring for reduced oil consumption.

Specifications:

Vehicle Fitment:

Additional hardware may be required (ECU, sensors, ancillaries, covers, pumps, etc.).

Sold individually. Head gasket kit (PN# IAG-ENG-1740) required and sold separately. Lead times may vary — contact us for current availability.