IAG 1150 Closed Deck Long Block Engine w/ IAG 1150 Heads

IAG 1150 Closed Deck Long Block Engine for 02-14 WRX, 04-21 STI, 04-13 FXT, 05-09 LGT

GSC S3 Camshafts REQUIRE Standalone Engine Management, May Not Be Compatible with AVCS. We also offer the S2 version of this long block here.

A “DROP-IN” SOLUTION

The IAG Performance hand-built Subaru EJ25 Closed Deck Long Block Engine package is a complete, valve cover-to-valve cover crate engine designed for a straightforward drop-in installation. This long block is ideal for Subaru WRX, STI, Forester XT, and Legacy GT platforms that require a high-performance, ready-to-install assembly. When paired with our Long Block Installation Packages, you’ll have a plug-and-play solution to get you back on the road fast. All components are BRAND NEW and there is NEVER a core charge required. 

BUILT WITH 100% NEW COMPONENTS

The IAG 1150 package supports up to 1150 BHP applications. It includes an IAG 1150 Closed Deck Short Block built from a brand new Subaru EJ25 case that is converted to closed deck and bored and honed to 99.75mm. The block features 14mm head stud machining and our Fire-Lock™ gasket solution, which provides maximum sealing for turbocharged Subaru engines. Internals include IAG-Spec JE FSR 2618 forged pistons with electroless nickel plating, H13 tool steel wrist pins, IAG-spec Tri-Beam connecting rods with ARP 625+ rod bolts, an IAG-Spec billet crankshaft, and ARP main bolts. 

The short block is paired with IAG 1150 Fully CNC Ported Cylinder Heads to maximize airflow for high horsepower applications. These heads begin as new Subaru OEM castings that are CNC ported, resurfaced, and fitted with Ferrea Comp Plus oversized valves, Ferrea Dual Drag springs with titanium retainers, GSC manganese bronze valve guides, and GSC Stage 2 camshafts with Kelford DLC-coated lifter buckets. A 14mm ARP head stud set and all required gaskets are included for the final valve cover-to-valve cover assembly. 

IAG 1150 EJ25 2.5L CLOSED DECK SUBARU SHORT BLOCK

BUILT TO WITHSTAND HIGH HORSEPOWER

The IAG 1150 Short Block is engineered to handle extreme power levels and rigorous applications such as drag racing. It includes Stage 4 closed decking, pinned mains with ARP case hardware, and our Fire-Lock™ head gasket system to ensure a reliable seal even under high boost. IAG-Spec forged components, a billet crankshaft, and race bearings provide strength and durability for competitive performance use. 

STRONGEST PISTONS EVER

The short block uses IAG-Spec JE 99.75mm FSR 2618 custom forged pistons treated with electroless nickel plating for durability and resistance to detonation. Equipped with .250" / .927" H13 tool steel wrist pins, these pistons offer substantial strength where it’s needed most for high-boost applications. 

IAG 1150 CNC PORTED DRAG CYLINDER HEADS

MAXIMUM POWER FOR DRAG RACING

The IAG 1150 CNC Ported Drag Cylinder Heads are designed for competition racing and high horsepower performance. Supporting up to 1150 BHP when paired with supporting modifications, these heads include Ferrea Comp Plus oversized intake and exhaust valves, Ferrea Dual Drag Valve Springs with titanium retainers, upgraded valve guides, and camshaft options from GSC. The CNC porting process delivers consistent, high-flow results that manual porting cannot match.

BUILT WITH 100% NEW COMPONENTS

Each head set starts with new OEM castings from Subaru of America, CNC ported on an in-house Centroid 5-axis machine, then undergoes machining for cam clearance, 14mm head studs, multi-angle valve jobs, resurfacing, ultrasonic cleaning, and final assembly with high-quality valve train components. 

IAG 1150 CLOSED DECK LONG BLOCK INCLUDES

IAG 1150 Closed Deck EJ25 Short Block:

• Case Halves – Converted to Closed Deck from new OEM Subaru case halves, bored & honed to 99.75mm
• Pinned Mains – Machined for 9.5mm pinned mains with ARP hardware
• Fire-Lock™ – Head gasket receiver groove machining (IAG Fire-Lock™ head gaskets required)
• Head Studs – Machined for 14mm head studs
• Pistons – IAG-Spec JE FSR 2618 forged pistons with electroless nickel plating, ring set & wrist pins
• Connecting Rods – IAG-Spec +2mm Tri-Beam with ARP 625+ bolts
• Rod/Main Bearings – ACL or King race bearings
• Crankshaft – IAG-Spec billet crank
• Case/Main Bolts – ARP bolts

IAG 1150 Fully CNC Ported Cylinder Heads:

• Heads – New OEM Subaru WRX STI castings
• Machine Porting – CNC ported intake & exhaust runners
• Intake Valves – Ferrea 37mm (+1mm) Comp Plus
• Exhaust Valves – Ferrea 33mm (+1mm) Comp Plus
• Springs/Retainers – Ferrea Dual Drag Valve Springs & titanium retainers
• Guides – GSC manganese bronze valve guides
• Valve Seals – GSC valve stem seals
• Lifters – Kelford DLC-coated lifter buckets
• Camshafts – GSC Stage 2 billet camshafts
• Multi-Angle Valve Job
• Machined Cam Lobe Clearance
• Drilled for 14mm Head Studs
• Resurfaced & Ultrasonically Cleaned
• Final Lash Adjustment

Gaskets, Hardware & Accessories:

• Head Studs – IAG / ARP 14mm set
• Head Gaskets – IAG Fire-Lock™
• Valve Cover Gaskets – OEM
• Cam Seals – OEM
• Valve Covers – OEM
• Wrist Pin Seal, Rear Main Seal & Separator Kit
• Crankshaft Woodruff Key

Please Note: This item is not eligible for standard ground shipping and must be delivered via freight. 
STOCK NOTICE: This item is built to order and carries a minimum 6-8 week build time.

IMPORTANT DELIVERY NOTE: Your order is shipping Via Truck Freight which requires you to be available at the time of receipt. There is a possibility the trucking company will try to schedule a delivery time with you. At the time of delivery, the driver will hand you the delivery receipt also referred to as the bill of lading, you will use this to notate any damages to the shipment. It is important that you fully inspect the shipment from all sides and notate any dents, punctures or rips in the outside packaging on the delivery receipt. Once you've inspected your shipment from the outside, you will need to open it and check the product in its entirety for damages and notate them if any. If there is no damage sign for the package and enjoy! In the rare case, you do find that your order arrived with damages, it is important you follow these steps. - Do not refuse the product- Document the damages in as much detail as possible on the Bill of Lading
- Take numerous photos from all angles (including packaging)
- Keep the product and contact the shipping company to start the damage claim
- Contact us either by phone or email for the next steps In the situation where the delivery driver is unable to wait for you to open and inspect your product, simply document "driver was unable to wait for inspection." All damage must be noted on the Bill of Lading before signing and initiating a damage claim. If the damage is not notated before signing for the item it is assumed to be in good condition. This will forfeit the ability for a shipping claim and you will not be eligible for refund or replacement.