$50.85
$100.17
Specifications Part Details: The IAG 1150 Closed Deck EJ25 Short Block represents the highest tier of engine foundation for Subaru EJ25 applications, built for extreme horsepower and competitive motorsport use. Rated for builds targeting up to 1,150 BHP, this short block is engineered to handle sustained high boost, elevated RPM, and severe engine loads where lower-tier EJ blocks reach their limits. Designed for drag racing, big-turbo street builds, and serious track applications, the IAG 1150 combines a reinforced closed-deck case with race-grade internals and precision machining to deliver maximum strength, stability, and long-term durability at extreme power levels. Closed Deck, Pinned Mains & Fire-Lock Design At the core of the IAG 1150 is a fully CNC-machined closed-deck EJ25 case that provides exceptional cylinder wall support under extreme cylinder pressure. To further enhance bottom-end rigidity, the case is machined for 9.5mm pinned mains and line-honed, reducing main cap movement under heavy load. For head gasket sealing at extreme boost levels, the block features IAG Fire-Lock™ receiver groove machining. This system is designed to work in conjunction with IAG Fire-Lock™ head gaskets and is critical for maintaining combustion sealing in high-horsepower, high-boost EJ builds. Engine Internals & Construction Internally, the IAG 1150 is assembled using race-focused components selected for maximum strength and durability. The short block features IAG-spec JE FSR forged pistons manufactured from 2618 alloy, with electroless nickel-plated crowns and ring lands for improved resistance to heat and detonation. High-strength H13 wrist pins are used to support extreme cylinder pressure and high RPM operation. IAG-spec 2mm Tri-Beam connecting rods with ARP 625 rod bolts provide exceptional rigidity, while an IAG-spec billet crankshaft replaces the factory-style unit to further increase strength and reliability in extreme power applications. ACL or King race bearings and ARP main bolts complete the bottom-end assembly. Each short block is fully blueprinted, bored, honed, and assembled in-house by IAG technicians to ensure precise tolerances, consistent oil clearances, and repeatable performance at the highest power levels. Reliability & Performance Benefits At power levels exceeding four digits, OEM-based EJ engine architecture becomes a significant limitation. The IAG 1150 addresses these challenges by combining closed-deck cylinder support, pinned mains, Fire-Lock sealing technology, and billet rotating components to create a foundation capable of withstanding extreme boost and sustained competition use. This short block is intended for builders who require maximum reliability in aggressive motorsport environments where failure is not an option. Vehicle Fitment Overview This short block is compatible with turbocharged Subaru EJ25 platforms, including WRX, WRX STI, Legacy GT, and Forester XT models. Full year-by-year compatibility is listed in the Vehicle Fitment tab above. This is a race-focused performance short block, not a stock replacement. Vehicle configuration, cylinder head selection, and overall build strategy should always be verified prior to purchase. What’s Included Brand-new Subaru OEM EJ25 case halves converted to closed deck, bored and honed to 99.75mm Machined for 9.5mm pinned mains and line-honed IAG Fire-Lock™ receiver groove machining (Fire-Lock™ head gaskets required) Machined for 14mm head studs IAG-spec JE FSR 99.75mm 2618 forged pistons with electroless nickel-plated crowns and ring lands 0.250″ / 0.927″ H13 wrist pins with clips and skirt coating IAG-spec 2mm Tri-Beam connecting rods with ARP 625 rod bolts ACL or King race rod and main bearings IAG-spec billet crankshaft ARP main bolts Compression Ratio 8.5:1 – EJ255 (D heads) 8.2:1 – EJ257 (B, V, W heads) with standard thickness head gasket Required Components IAG Fire-Lock™ 0.051″ head gaskets with IAG-spec alloy ring set (PN: IAG-ENG-1741) 14mm head studs (required) Installation & Build Notes Professional installation is mandatory at this power level ECU tuning is required Comprehensive supporting modifications (fuel system, turbo system, cooling, oiling) are essential Final power capability depends on the complete engine build, tuning strategy, and operating conditions Recommended Supporting Upgrades Air / Oil Separator and Oil Catch Cans – Helps reduce oil vapor ingestion and protect the intake system under high boost. Oiling Upgrades – Improve oil control and reduce bearing failure risk in high RPM and high load builds. Gaskets & Seals – Recommended for proper sealing during assembly and installation at this power level. Hardware & Fasteners – Supporting hardware, studs, and fasteners commonly required during install. Build Planning Resources Before committing to a short block, understanding your engine’s current limits and upgrade path is critical. These guides cover the key decisions most WRX and STI builders face before selecting internals. How Much Power Can a Stock FA20 and FA24 Handle? – Know your stock limits before deciding when an IAG short block becomes the right move. Short Block vs Long Block: Which Do You Need? – Understand the difference and which option fits your power goals and rebuild strategy. FA20 vs FA24: Which Engine Is Worth Building? – Platform comparison covering power potential, reliability, and upgrade paths. Performance Airflow Upgrades Corsa Veloce Stradale Rear-Facing Intake Manifold– increases airflow and supports high-horsepower EJ engine builds Why Buy Your IAG 1150 Closed Deck Short Block from Wrench Masters? At Wrench Masters, we specialize in Subaru performance builds and high horsepower engine setups. When you purchase your IAG 1150 closed deck short block from us, you get: Fast shipping on in-stock performance engines Support for WRX, STI, LGT, and FXT build planning Guidance on fueling, turbo pairing, and tuning strategy Help selecting supporting upgrades for 1000 BHP goals This is not just an engine purchase. We help you plan the full build so your setup is reliable, balanced, and ready for the power level you want. Learn more about IAG Performance engine and reliability solutions Shipping Shipping Options: WrenchMastersAuto.com ships your performance parts safely, quickly and conveniently nationwide via the most trusted shipping carriers such as: UPS, Fed Ex, USPS, and DHL. Delivery Times: In Stock: 3-7 Business Days Custom Orders: 2-6 Weeks, Please Email: [email protected] or Call: 727-565-9808 for Questions. Enjoy FREE SHIPPING on most orders over $199! Contact WrenchMasters Have Questions? Need Assistance? 727-565-9808 Our expert team members are available Mon-Friday 8:00 AM to 5:30 PM EST to provide support and answer any questions or concerns before or after your parts purchase. Part Installation Want your performance parts professionally installed? Save time, stress & hassle by scheduling your auto appointment online below. Our team of ASE certified master techs will make sure your parts are installed properly at our St.Petersburg, Florida shop location. Schedule Install Now Performance Parts Locator Looking for a specific part not listed on our online store? WrenchMastersAuto.com has access to over 40,000 aftermarket performance parts for vehicles of all makes and models, old and new. Fill out the parts request form below, and our parts specialist will contact you within 24-48 hours.
Assembled Short Blocks
