Stage 4 EXTREME 2.5L Subaru Closed Deck Short Block

The IAG Performance Stage 4 EXTREME 2.5L Subaru Closed Deck Short Block is a professionally built and assembled engine block engineered to withstand higher boost pressures and power outputs, making it an ideal choice for high-performance street or dedicated race vehicles. It is constructed from brand new Subaru OEM case halves that have been converted to a closed deck design for enhanced strength. Key specifications include a 99.75mm bore size, a 2.5L displacement, and forged aluminum pistons. This short block is fitted with IAG-Spec JE FSR pistons, .250″ / .927″ H13 performance wrist pins, IAG Spec Tri-Beam connecting rods with ARP625+ rod bolts, ACL rod and main bearings, and a Manley Billet Turbo Tuff Crankshaft. It is machined to accept 14mm head studs, which are sold separately. The compression ratio can vary depending on the cylinder heads used: 8.2:1 is achieved with B, V, and W cylinder heads (EJ257), while D cylinder heads (EJ255) result in an 8.5:1 compression ratio. This build requires IAG Fire-Lock Head Gaskets for optimal performance in high boost applications. The engine is blueprinted and assembled with precision, utilizing a Haas VF-4SS mill for the closed deck inserts and final finishing touches for the IAG Fire-Lock head gaskets. This short block is compatible with 2002-2005 Subaru WRX, 2004-2014 Subaru Impreza (including STI models), and 2004-2013 Subaru Forester models. It is specifically designed for EJ257 engines and may require specific cylinder heads for the stated compression ratios.