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IAG : Performance 1150 EJ25 Closed Deck Short Block - (EJ25)

IAG : Performance 1150 EJ25 Closed Deck Short Block - (EJ25)

Regular price $16,499.95 AUD
Regular price Sale price $16,499.95 AUD
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The IAG 1150 Long Block has a power output rating of 1150BHP.


The IAG 1150 Short Block is designed for those who plan to drag race their high horsepower Subarus regularly. While still a streetable block, the IAG 1150 is designed for the track. This block includes additional features to further strengthen the OEM case halves including Stage 4 Closed Decking and pinned mains secured with ARP case hardware. Our record-setting "Fire-Lock" Head Gasket system and 14mm head studs are used to ensure a tight seal even in extreme conditions. The IAG 1150 Short Block features IAG Spec "Tri-Beam" +2mm forged connecting rods. An IAG Spec Billet Crankshaft is used to support additional oiling and prevent main bearing distortion. The upgraded block, billet crank, connecting rods, race bearings, and forged pistons are able to support additional engine load produced by the largest turbochargers and the most demanding uses including competition drag racing.


Every IAG Short Block is built with 100% new components. The modified case halves are assembled using an IAG-Spec Billet crankshaft that is matched to ACL or King race main bearings. Custom IAG TRI-BEAM +2mm connecting rods with ARP 625+ rod bolts are utilized, along with ACL or King race rod bearings. The case halves are sealed with OEM sealant and ARP main bolts. The IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins as well as electroless nickel plated tops and ring area are chosen to finish the Stage 4 Extreme Short Block.


The IAG 1150 Short Block starts with brand new Subaru 2.5L EJ25 engine case halves. The case halves are split and the main webs are CNC machined in our Haas VF-4SS CNC mill for 9.5mm pins to reduce distortion and movement of the case in extreme conditions. The case halves are then reassembled and IAG machines the case 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-Lockā„¢ 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 IAG 1150 case is CNC drilled and tapped to fit 14mm head studs. Utilizing the new Fire-Lockā„¢ gasket solution, along with larger IAG / ARP 14mm head studs, nuts, and washers reduce the chances of the heads lifting under extreme boost conditions. The short block is then Deck Plate bored and honed to 99.75mm in our in-house Sunnen SV-30 cylinder hone. IAG's in-house honing process is able to set custom piston to wall clearances to ensure performance an reliability.


Our unique closed deck system significantly increases the strength of the OEM case halves. This process supports the cylinder walls at the top of the case in order to prevent flexing and possible cracking where the case bolt reliefs are cut into the back of the cylinder wall.
During the installation process we machine the assembled case halves in our Haas VF-4SS CNC mill to accept the IAG Closed Deck inserts. Once the case has been machined we heat it in an oven while freezing the specially machined inserts with liquid nitrogen. The inserts are then pressed into place and then machined to a mirror finish.
The unique inserts feature small passages that allow needed coolant flow to the deck surface. This means that the closed deck system does not affect the block's cooling ability and will not cause overheating, even in daily drivers.


The IAG 1150 Short Block uses our strongest pistons ever - The IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins feature electroless nickel plated tops and ring area. IAG's custom pistons feature a lightweight design while increasing strength where you need it and are designed to work exclusively with the IAG +2mm Tri-Beam connecting rods. The wrist pin is short and is made from strong H13 tool steel. The pin piers are profiled to increase pin boss strut. Finally, IAG's pistons feature a 25% larger oil ring for reduced oil consumption and added gas ports that aid ring sealing in high boost conditions.

IAG 1150 Closed Deck EJ25 Short Block:

  • Case Halves -Ā Converted to Closed Deck from brand new OEM Subaru case halves, bored and honed to 99.75mm.
  • Pinned Mains -Ā Machine case for 9.5mm pinned mains and lined honed.
  • Fire-Lockā„¢ -Ā IAG Fire-Lockā„¢ receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subaru's - *IAG Fire-Lockā„¢ head gaskets required
  • Head Studs -Ā Machined for 14mm Head Studs.
  • Pistons -Ā 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 -Ā IAG-Spec +2mm Tri-Beam Connecting Rods with ARP 625+ Rod Bolts.
  • Rod / Main Bearings -Ā ACL or King Race Bearings.
  • Crank -Ā IAG-Spec Billet Crank
  • Case / Main Bolts -Ā ARP Main Bolts.

Head Gasket Required (Sold Separately):

  • *IAG Fire-Lockā„¢ .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1740

Compression Ratio:

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

Vehicle Fitment:

Additional hardware may be required to install this long block to the following vehicles, including but no limited to ECU, Sensors, Ancillaries, Covers, Pumps etc.

  • 1999-2014 Subaru WRX (w/EJ25 Heads)
  • 1999-2021 Subaru STI (w/EJ25 Heads)
  • 1997-2013 Subaru Forester XT (w/EJ25 Heads)
  • 2004-2009 Subaru Liberty GT (w/EJ25 Heads)
  • 2004-2009 Subaru Outback XT (w/EJ25 Heads)
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