IAG 950 EJ25 2.35L Destroked Closed Deck Short Block - 950 BHP

IAG 950 EJ25 2.35L Destroked Closed Deck Short Block for 02-14 WRX, 04-21 STI, 05-09 LGT, 04-13 FXT

THE IAG 950 EJ25 2.35L DESTROKED CLOSED DECK SHORT BLOCK

IAG’s 950 EJ25 2.35L Destroked Closed Deck Short Block delivers track-level power, supporting up to 950 BHP, while still offering the dependability needed for everyday driving. This hand assembled block is based off of our IAG 950 Short Block, and features a 2.0L FHI crankshaft, custom IAG Spec +2mm H-beam forged connecting rods and ARP 625+ rod bolts. Also included in the assembly are JE 99.75mm FSR 2618 custom pistons that have been treated with electroless nickel-plating, creating a hard-wearing surface that offers detonation resistance and heat reflection. This short block strikes the perfect balance for street use along with high-revving racing applications, offering unmatched reliability and longevity. :contentReference[oaicite:0]{index=0}

DESTROKED FOR HIGH-REVVING APPLICATIONS

Featuring a shorter stroke, these +2 rod engines reduce piston speeds, optimizing the rod-to-stroke ratio and increasing piston dwell time at top dead center. In terms of performance, this means increased power output, extended ring life, and the ability to rev up to 8,500 RPM, making this short block an ideal choice for track days, rally events, or drag racing applications. :contentReference[oaicite:1]{index=1}

CLOSED DECK WITH 100% NEW COMPONENTS

The IAG 950 EJ25 Short Block starts with brand new Subaru 2.5L engine case halves. Our expert machinists machine the assembled case halves in our Haas VF-4SS CNC mill to accept the IAG Closed Deck inserts, transforming the block into a solid deck. Next, a deck pair of deck plates are attached and the short block is bored and honed to 99.75mm in our in-house Sunnen SV-30 computer controlled cylinder hone. IAG’s in-house honing process allows us to set custom piston-to-wall clearances to ensure quiet operation and reduced oil consumption. The Haas mill also cuts a groove at the top of each cylinder to accept the Fire-Lock™ head gasket rings and drills each head bolt hole for 14mm head studs. The modified case halves are then assembled using a new 2.0L FHI crankshaft, custom IAG Spec +2mm H-beam forged connecting rods and ARP 625+ rod bolts, along with JE 99.75mm FSR 2618 custom pistons. IAG Short Blocks feature ACL rod and main bearings and are all balanced and blueprinted. Finally, the case halves are sealed with new OEM main/case bolts and sealant. :contentReference[oaicite:2]{index=2}

IAG’S FIRE-LOCK™ SYSTEM: NO MORE HEAD GASKET WORRIES

The IAG 950 EJ25 2.35L Destroked Closed Deck Short Block features our proprietary “Fire-Lock™” Head gasket system. This system has been proven in our record setting race cars to be the strongest Subaru head gasket system ever produced. To achieve these results, our engineers separated the combustion chamber sealing from the fluid sealing aspects of the head gaskets. Our machinists carefully machine a lip at the top of each cylinder to accept the “Fire-Lock™” ring. With the ring locked in place, it stands proud above the deck, providing a superior seal. The separate gasket bodies take care of sealing oil and coolant passages and keeping them out of the combustion chamber. 14mm head studs (not included) hold the assembly together. :contentReference[oaicite:3]{index=3}

CLOSED DECK FOR EXTRA STRENGTH

Our innovative closed deck system significantly increases the strength of the OEM case halves. This process supports the cylinder walls at the top of the case in order to prevent flexing and possible cracking where the case bolt reliefs are cut into the back of the cylinder wall. During the installation process, we machine the assembled case halves in our Haas VF-4SS CNC mill to accept the IAG Closed Deck inserts. Once the case has been machined we heat it in an oven while freezing the specially machined inserts with liquid nitrogen. The inserts are then pressed into place and then machined to a mirror finish. Our distinctive inserts feature small passages that allow needed coolant flow to the deck surface. This means that the closed deck system does not affect the block’s cooling ability and will not cause overheating, even in daily drivers. :contentReference[oaicite:4]{index=4}

CUSTOM JE PISTONS

The IAG 950 Short Block features JE 99.75mm FSR 2618 custom pistons, engineered to deliver outstanding performance for both street driving as well as drag and rally racing applications. These pistons feature thicker ringlands and are treated with electroless nickel-plating, resulting in a stronger piston that can stand up to highly boosted applications. Additionally, they come equipped with .240" H13 tool steel wrist pins, providing a significant upgrade over standard chromoly pins, ensuring enhanced reliability under extreme conditions. :contentReference[oaicite:5]{index=5}

BUILT TO PERFORM

A common failure point of the OEM Subaru short block are the piston ringlands. The metal ledges on the pistons that hold the compression rings in place can withstand regular usage but are prone to failure when used with modified components. Cracked or broken ringlands often lead to increased oil consumption and eventual bearing failure if the oil is not closely monitored. In contrast, the increased ringland thickness on the custom JE pistons used in the IAG 950 Short Block are designed to match up to 950’s capabilities, ensuring durability and reliability even under high-performance conditions. :contentReference[oaicite:6]{index=6}

PROFESSIONALLY ASSEMBLED AND READY TO INSTALL

Our team of certified Subaru specialists at IAG Performance takes great care in assembling each IAG 950 Short Block. These specialists have built over 14,000 Subaru engines and counting. Equipped with an advanced selection of tooling and state-of-the-art equipment, we guarantee the quality of all our engine blocks. Each block is meticulously crafted and thoroughly checked, ensuring the highest standards of quality assurance. IAG’s hand-assembled Short Blocks make it easy to upgrade your EJ25 Subaru engine — just leave the technical work to us, and we’ll provide you with a superior short block that’s ready to install. :contentReference[oaicite:7]{index=7}

IAG 950 DESTROKED CLOSED DECK SHORT BLOCK INCLUDES

What's Inside:

• Case Halves – Brand new Subaru OEM case halves
• 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 – Machined for 14mm head studs (*studs sold separately)
• Pistons – JE 99.75mm FSR 2618 custom pistons and .240" H13 tool steel wrist pins with JE Pro Seal ring set
• 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)
• 8.8:1 on B, V, and W EJ257 Heads

Power Rating:

Power: The IAG 950 EJ25 2.35L Destroked Closed Deck Short Block has a power output rating of 950 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.