IAG 1150 EJ25 2.35L Destroked Closed Deck Short Block - 1150 BHP

IAG 1150 EJ25 2.35L Destroked Closed Deck Short Block for 02-14 WRX, 04-21 STI, 05-09 LGT, 04-13 FXT

THE IAG 1150 DESTROKED CLOSED DECK SHORT BLOCK

The IAG 1150 EJ25 2.35L Destroked Closed Deck Short Block is built for high horsepower and high RPM applications. The shorter stroke and optimized rod-to-stroke ratio allow for increased piston dwell time at top dead center, improving ring life and power output. This configuration also increases rev limits and is ideal for experienced racers and competition vehicles seeking extreme performance characteristics. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

BUILT WITH 100% NEW COMPONENTS

Like all IAG short blocks, this assembler begins with brand new Subaru 2.5L engine case halves. The assembled case halves are machined in our Haas VF-4SS CNC mill to accept the IAG Closed Deck inserts, transforming the block into a solid deck configuration. Next, a deck pair of plates are attached and the block is bored and honed to a 99.75mm finish using IAG’s in-house Sunnen SV-30 cylinder hone. This controlled process allows IAG to set custom piston-to-wall clearances to optimize durability and oil consumption. The closed deck installs feature precision fit, and coolant passages are preserved to maintain proper cooling characteristics. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

IAG’S FIRE-LOCK™ HEAD GASKET SYSTEM

The IAG 1150 Destroked block includes IAG’s proprietary Fire-Lock™ head gasket system, which separates the combustion sealing from fluid sealing to greatly increase reliability under high cylinder pressure. A precision machined lip at the top of each cylinder accepts the Fire-Lock™ ring, which stands above the deck and creates a superior seal. The separate head gasket bodies then handle fluid sealing for oil and coolant passages. While 14mm head studs are not included, the case is CNC machined for their installation to further enhance sealing integrity. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

CLOSED DECK FOR MAXIMUM STRENGTH

The closed deck system significantly increases the strength of the Subaru EJ25 case halves by supporting the cylinder walls at the top of the case, reducing flexing and the potential for cracking near case bolt reliefs. The inserts are installed at elevated temperatures while frozen so they press into place cleanly, then are machined to a mirror finish. Small passages are included in the inserts to maintain coolant flow and prevent heat-soak under real-world driving conditions. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

CUSTOM JE FSR FORGED PISTONS

The IAG 1150 Destroked Short Block uses JE 99.75mm FSR 2618 custom forged pistons, which provide enhanced strength and detonation resistance. These pistons feature thicker ringlands and are finished with electroless nickel plating, offering a strong but lightweight design suited for high-boost, high-RPM environments. The pistons are equipped with .240" H13 tool steel wrist pins and a JE ProSeal ring set, making them capable of handling demanding racing conditions. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

PROFESSIONALLY ASSEMBLED AND READY TO INSTALL

Like all IAG Performance’s short blocks, the 1150 Destroked version is hand assembled by certified technicians experienced with Subaru engines. Balanced and blueprinted with precise tolerances, this short block arrives ready for installation. A new 2.0L FHI crankshaft, custom IAG Spec +2mm H-Beam forged connecting rods, and ACL race bearings form a rugged rotating assembly for serious builds. ([iagperformance.com](https://www.iagperformance.com/iag-1150-destroked-2-35l-subaru-closed-deck-short-block-for-wrx-sti-lgt-fxt-1150-bhp/))

IAG 1150 DESTROKED CLOSED DECK SHORT BLOCK INCLUDES

What's Inside:

• Case Halves – Brand new Subaru OEM EJ25 case halves, converted to Closed Deck
• Fire-Lock – IAG Fire-Lock™ receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subarus (IAG Fire-Lock™ head gaskets required)
• Head Studs – Machine case for 14mm head studs (*studs sold separately)
• Pistons – JE 99.75mm FSR 2618 custom pistons, electroless nickel plated tops & ring area, ring set, .240" H13 wrist pins
• Connecting Rods – Custom IAG Spec +2mm H-Beam forged connecting rods with ARP 625+ rod bolts
• Rod / Main Bearings – ACL race bearings
• Crankshaft – 2.0L FHI crankshaft
• Case / Main Bolts – Standard FHI Subaru case bolts

Compression Ratio:

• 9.2:1 on D Cylinder Heads (EJ255)
• 8.6:1 on B, V, and W EJ257 heads

Power Rating:

Power: The IAG 1150 EJ25 2.35L Destroked Closed Deck Short Block has a power output rating of 1150 BHP

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.