IAG 1150 2.5L Subaru Short Block - Subaru Models (Inc. 2002-2021 Subaru WRX / 2004-2021 STI / 2004-2013 Forester)

ENGINEERED FOR HIGH-HORSEPOWER DRAG RACING

Tailored for enthusiasts who frequently participate in drag racing with their high-horsepower Subarus, the IAG 1150 Short Block is meticulously crafted. While still suitable for street use, the primary focus of the IAG 1150 lies in track performance. This block integrates advanced features to reinforce the OEM case halves, such as Stage 4 Closed Decking and pinned mains secured with ARP case hardware. Our renowned "Fire-Lock" Head Gasket system and 14mm head studs are utilized to ensure a reliable seal, even under the most extreme conditions. Equipped with IAG Spec "Tri-Beam" +2mm forged connecting rods, this short block guarantees exceptional durability. To address additional oiling needs and prevent main bearing distortion, an IAG Spec Billet Crankshaft is employed. With upgraded components like the block, billet crank, connecting rods, race bearings, and forged pistons, the IAG 1150 Short Block is engineered to withstand the heightened engine load posed by the largest turbochargers and the most demanding applications, including competitive drag racing.

IAG 1150 CLOSED DECK WITH FIRE-LOCK SYSTEM

The IAG 1150 Short Block is built upon brand new Subaru 2.5L EJ25 engine case halves. These halves undergo a detailed process, including CNC machining of the main webs using our Haas VF-4SS CNC mill with 9.5mm pins to minimize distortion and movement in extreme conditions. After reassembly, the case is machined to integrate IAG CLOSED Deck Inserts, converting it into a solid deck. These inserts include small passages for essential coolant flow. CNC machining is then employed to implement the innovative Fire-Lock™ head gasket solution, inspired by diesel technology, which involves creating a counterbore step around each cylinder bore to accommodate specially sized fire rings for optimal sealing. Additionally, the case is drilled and tapped to fit 14mm head studs, enhancing stability under high boost conditions. By utilizing the Fire-Lock™ gasket solution and larger IAG / ARP 14mm head studs, nuts, and washers, the risk of head lifting is minimized. Finally, the short block undergoes Deck Plate boring and honing to 99.75mm using our in-house Sunnen SV-30 cylinder hone, with custom piston-to-wall clearances set to ensure both performance and reliability.



MOST ROBUST PISTONS YET

The IAG 1150 Short Block is equipped with our toughest pistons to date: The IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins, featuring electroless nickel-plated tops and ring areas. Engineered for maximum strength and endurance, these custom pistons from IAG are designed with a lightweight build while reinforcing crucial areas where strength is paramount, specifically engineered to complement the IAG +2mm Tri-Beam connecting rods. Crafted from durable H13 tool steel, the wrist pin is deliberately short, enhancing pin boss strut via profiled pin piers. Moreover, IAG's pistons boast a 25% larger oil ring to minimize oil consumption, coupled with additional gas ports that enhance ring sealing, particularly under high boost conditions.

IAG 1150 Closed Deck EJ25 Short Block Includes:

Case Halves -Converted to Closed Deck from brand new OEM Subaru case halves, bored and honed to 99.75mm.
Pinned Mains -Machine case for 9.5mm pinned mains and lined honed.
Fire-Lock -IAG Fire-Lock™ receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subaru's - *IAG Fire-Lock™ head gaskets required
Head Studs -Machined for 14mm Head Studs.
Pistons -IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Electroless Nickel Plated Tops & Ring area, Ring Set, .250" / .927" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
Connecting Rods -IAG-Spec +2mm Tri-Beam Connecting Rods with ARP 625+ Rod Bolts.
Rod / Main Bearings -ACL or King Race Bearings.
Crank -IAG-Spec Billet Crank
Case / Main Bolts -ARP Main Bolts.


Compression Ratio:

8.5:1 on D Cylinder Heads (EJ255)
8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.


Head Gasket Required:

*IAG Fire-Lock™ .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1741