IAG 1150 High Compression 2.5L Subaru Closed Deck Short Block - 1150 BHP

IAG 1150 High Compression 2.5L Subaru Closed Deck Short Block for 02-14 WRX, 04-21 STI, 05-09 LGT, 04-13 FXT

THE IAG 1150 HIGH COMPRESSION SHORT BLOCK

Built for high-octane fuels such as E85 and race gas, the IAG 1150 High Compression 2.5L Closed Deck Short Block is the ideal choice for high-horsepower drag racing scenarios. While suitable for street use, it’s built to dominate the track. Compared to our regular 1150 Short Block pistons with compression ratios of 8.5:1 (D Heads, EJ255) and 8.2:1 (B, V, and W Heads, EJ257), the IAG High Compression 1150 steps it up to 9.9:1 on D Heads and 9.5:1 on B, V, and W Heads, unlocking more power and efficiency needed for race applications. :contentReference[oaicite:0]{index=0}

BUILT FOR SPEED AND POWER

This high compression Subaru block includes additional features to further strengthen the OEM case halves including Stage 4 Closed Decking and pinned mains secured with ARP case hardware. Our record-setting “Fire-Lock” Head Gasket system and 14mm head studs are used to ensure a tight seal even in extreme conditions. In addition, this short block also features IAG Spec “Tri-Beam” +2mm forged connecting rods. An IAG Spec Billet Crankshaft is used to support additional oiling and prevent main bearing distortion. The upgraded block, billet crank, connecting rods, race bearings, and forged pistons are able to support additional engine load produced by the largest turbochargers and the most demanding uses including competition drag racing. :contentReference[oaicite:1]{index=1}

BUILT WITH 100% NEW COMPONENTS

Every IAG Short Block is built with 100% new components. The modified case halves are assembled using an IAG-Spec Billet crankshaft that is matched to ACL or King race main bearings. Custom IAG Tri-Beam +2mm connecting rods with ARP 625+ rod bolts are utilized, along with ACL or King race rod bearings. The case halves are sealed with OEM sealant and ARP main bolts. :contentReference[oaicite:2]{index=2}

The IAG-Spec 99.75mm custom forged pistons with .250" wall / .927" diameter wrist pins as well as electroless nickel plated tops and ring area are chosen to finish the IAG 1150 High Compression Short Block. :contentReference[oaicite:3]{index=3}

IAG CLOSED DECK WITH FIRE-LOCK SYSTEM

The IAG 1150 High Compression Short Block starts with brand new Subaru 2.5L EJ25 engine case halves. The case halves are split and the main webs are CNC machined for 9.5mm pins to reduce distortion and movement of the case in extreme conditions. The case halves are then reassembled and IAG machines the case to accept the IAG Closed Deck inserts that transform the block into a solid deck. The unique inserts feature small passages that allow needed coolant flow to the deck surface. The case halves are then CNC machined for our new Fire-Lock™ head gasket solution that is loosely derived from diesel technology where a counterbore step is machined around each cylinder bore allowing specially sized fire rings to drop into the machined area and head gasket bores. The IAG 1150 case is CNC drilled and tapped to fit 14mm head studs. Utilizing the new Fire-Lock™ gasket solution, along with larger IAG / ARP 14mm head studs, nuts, and washers reduce the chances of the heads lifting under extreme boost conditions. The short block is then deck plate bored and honed to 99.75mm in IAG’s in-house Sunnen SV-30 cylinder hone. IAG’s in-house honing process is able to set custom piston-to-wall clearances to ensure performance and reliability. :contentReference[oaicite:4]{index=4}

STRONG & LIGHT DESIGN

The IAG 1150 High Compression Short Block uses IAG-Spec 99.75mm custom forged pistons with electroless nickel plated tops and ring area. IAG’s custom pistons feature a lightweight design while increasing strength where you need it and are designed to work exclusively with the IAG +2mm Tri-Beam connecting rods. The wrist pin is short and is made from strong H13 tool steel. The pin piers are profiled to increase pin boss strength. Finally, IAG’s pistons feature added gas ports that aid ring sealing in high boost conditions. :contentReference[oaicite:5]{index=5}

IAG HIGH COMPRESSION PISTONS

The IAG 1150 High Compression Short Block includes all the premium components of our 1150 short block, upgraded with custom high compression pistons. These pistons increase the compression ratio by reducing the pistons’ negative cc volume and changing from a “dish” to a “flat top” style piston, making them ideal for racing applications where power and efficiency matter most. To ensure optimal performance, this short block requires consistent use of high-octane fuels like E85 or race gas. Pump gas is suitable only during the break-in process. :contentReference[oaicite:6]{index=6}

IAG 1150 HIGH COMPRESSION SHORT BLOCK INCLUDES

What's Inside:

• Case Halves – Converted to Closed Deck from brand new OEM Subaru case halves, bored & honed to 99.75mm
• Pinned Mains – Machine case for 9.5mm pinned mains and line honed
• Fire-Lock – IAG Fire-Lock™ receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subaru’s (IAG Fire-Lock™ head gaskets required)
• Head Studs – Machined for 14mm head studs
• Pistons – IAG-Spec JE FSR 99.75mm 2618 forged pistons, electroless nickel plated tops & ring area, ring set, .250" wall / .927" diameter H13 wrist pins, clips (Perfect Skirt coating and offset wrist pins)
• Connecting Rods – IAG-Spec +2mm Tri-Beam connecting rods with ARP 625+ rod bolts
• Rod / Main Bearings – ACL or King race bearings
• Crank – IAG-Spec billet crank
• Case / Main Bolts – ARP main bolts

Compression Ratio:

• 9.9:1 on D Cylinder Heads (EJ255)
• 9.5:1 on B, V and W EJ257 Heads

Power Rating:

Power: The IAG 1150 High Compression 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.