Built for high-octane fuels such as E85 and race gas, the IAG 1150 High Compression 2.5L Closed Deck Short Block is the ideal choice for high-horsepower drag racing scenarios. While suitable for street use, it’s built to dominate the track. Compared to our regular 1150 Short Block pistons with compression ratios of 9.2:1 (D Heads, EJ255) and 8.8:1 (B, V, and W Heads, EJ257), the IAG High Compression 1150 steps it up to 9.9:1 on D Heads and 9.5:1 on B, V, and W Heads, unlocking more power and efficiency needed for race applications. This high compression Subaru 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. In addition, this short block also 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.

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: 9.9:1 on D Cylinder Heads (EJ255), 9.5:1 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