550 Long Block Engine

The IAG Performance Hand-Built 550 Subaru EJ25 Long Block Packages offer a complete, valve cover to valve cover crate engine solution for Subaru WRX, STI, Forester XT, and Legacy GT vehicles. Designed as a "drop-in" engine package, these long blocks simplify installation for customers seeking a high-performance replacement. The core of this package is the IAG 550 Short Block, which utilizes a brand new EJ25 Subaru case, 99.75mm IAG-Spec JE forged pistons, IAG Spec H-Beam connecting rods, and an OEM STI Crank. The IAG 550 Cylinder Head Package complements the short block, featuring Subaru WRX STI OEM cylinder head castings enhanced with GSC valvetrain components, including standard size valves, Viton valve stem seals, Stage 1 valve springs with titanium retainers, and OEM keepers. GSC S1 Billet Camshafts are also included to improve power and torque across the RPM range, suitable for upgraded turbos or up to 500 WHP applications. The assembly is completed with an 11mm ARP 2000 head stud set and all necessary gaskets for a full valve cover-to-valve cover assembly. This long block is specifically engineered to support applications up to 550 BHP, with the IAG 550 Short Block designed to withstand increased cylinder pressures from higher boost levels. The use of IAG Spec H-Beam Connecting Rods with ARP2000 rod bolts and ACL or King race bearings ensures reliability under heavy load. All components are new, and there is no core charge required. Comprehensive timing component kits, available in Street or Competition versions, can be added for a complete and precise installation.