IAG 1150 2.35L DESTROKED LONG BLOCK ENGINE W/ IAG 1150 HEADS

IAG 1150 2.35L Destroked 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.

DROP IN AND DRIVE

The IAG Performance hand-built Subaru 1150 2.35L Destroked Long Block Engine package is a complete, valve cover-to-valve cover crate engine. This engine provides a straightforward “drop-in” solution for those looking to upgrade their 2002–2014 Subaru WRX, 2004–2021 Subaru STI, 2004–2013 Subaru FXT, or 2005–2009 Subaru LGT. This long block features a combination of our proven IAG EJ25 2.35L Destroked Closed Deck Short Block and IAG 1150 Cylinder Head packages, along with a full range of carefully selected high-performance components. When paired with our Long Block Installation Packages, you’ll have a true plug-and-play solution to get you back on the road, FAST! All components included are BRAND NEW and there is NEVER a CORE CHARGE required. 

HAND-BUILT WITH 100% NEW COMPONENTS

IAG’s 1150 2.35L Destroked Long Block Engine delivers track-level power, making it ideal for high-performance applications that support up to 1150 BHP. This comprehensive long block package features an IAG 1150 Closed Deck Short Block built from a brand new Subaru EJ25 engine case that is converted to closed deck and bored and honed to 99.75mm. The block includes 14mm head stud machining and IAG’s Fire-Lock™ gasket solution derived from diesel technology, allowing specially sized fire rings to drop into machined receiver grooves for maximum sealing. Internals include custom JE 99.75mm FSR 2618 pistons, JE Pro Seal Ring Set, .240" H13 tool steel wrist pins, custom IAG-spec +2mm Tri-Beam forged connecting rods, IAG-spec billet 75mm crankshaft, ACL race bearings, and ARP case bolts.

The short block is paired with IAG 1150 Fully CNC Ported Cylinder Heads for maximum flow and performance. These heads begin as new Subaru OEM castings, CNC machined inside intake and exhaust runners, resurfaced, and outfitted with high-quality valve train components that include +1mm oversized Comp Plus intake and exhaust valves, Ferrea Dual Drag valve springs with titanium retainers, GSC manganese bronze valve guides, and GSC Stage 2 camshafts with Kelford DLC-coated lifter buckets. Final assembly includes a 14mm ARP head stud set, Fire-Lock™ head gasket solution, and all required gaskets for the full valve cover-to-valve cover assembly. 

IAG 1150 EJ25 2.35L DESTROKED CLOSED DECK SHORT BLOCK

TRACK-OPTIMIZED PERFORMANCE

The IAG 1150 EJ25 2.35L Destroked Closed Deck Short Block is engineered to handle intense loads generated by high-boost setups and large turbochargers, supporting up to 1150 BHP. Built on an IAG-spec billet 75mm crankshaft with custom +2mm Tri-Beam rods and ARP 625+ rod bolts, it also includes JE 99.75mm FSR 2618 pistons treated with electroless nickel plating for detonation resistance and heat reflection. This combination provides a rock-solid foundation capable of enduring race conditions and extreme engine loads.

DESTROKED ADVANTAGES

The destroked configuration reduces piston speed, optimizes rod-to-stroke ratio, increases piston dwell time at top dead center, and improves combustion efficiency. These benefits yield increased power output, extended ring life, and the ability to safely rev higher—making this short block ideal for track days and competition drag racing. 

CLOSED DECK STRENGTH

The IAG 1150 closed deck system significantly increases case strength by supporting cylinder walls where case bolt reliefs are commonly weak. Machining for closed deck inserts and precision assembly ensures the block maintains coolant flow without overheating, even in daily driver conditions.

IAG 1150 CNC PORTED DRAG CYLINDER HEADS PACKAGE

DESIGNED FOR DRAG POWER

The IAG 1150 CNC Ported Drag Cylinder Heads are designed for competition and high horsepower builds. Supporting up to 1150 BHP with the right supporting modifications, these heads include upgraded Ferrea Comp Plus valves, Ferrea Dual Drag valve springs with titanium retainers, GSC valve guides, and your choice of GSC S3 or S3 camshafts with Kelford DLC-coated lifter buckets.

PORTING & ASSEMBLY

Each head set starts with new OEM castings that are CNC ported on a Centroid 5-axis machine for consistent, high-flow results. Machining includes cam clearance, drilling for 14mm studs, multi-angle valve jobs, resurfacing, ultrasonic cleaning, and final assembly with high-quality valve train components. 

IAG 1150 DESTROKED LONG BLOCK INCLUDES

IAG 1150 EJ25 2.35L Short Block:

• Brand new Subaru OEM EJ25 case halves treated with closed deck conversion
• Pinned mains with ARP case bolts
• Fire-Lock™ head gasket receiver groove machining
• Machined for 14mm head studs
• JE 99.75mm FSR 2618 custom pistons
• .240" H13 tool steel wrist pins
• Custom IAG-spec +2mm Tri-Beam connecting rods with ARP 625+ bolts
• ACL race rod and main bearings
• IAG-Spec billet 75mm crankshaft

IAG 1150 Fully CNC Ported Cylinder Heads:

• New Subaru WRX STI OEM cylinder head castings
• CNC ported intake & exhaust runners
• Ferrea 37mm (+1mm) Comp Plus intake valves
• Ferrea 33mm (+1mm) Comp Plus exhaust valves
• Ferrea Dual Drag valve springs & titanium retainers
• GSC manganese bronze valve guides
• GSC valve stem seals
• Kelford DLC-coated lifter buckets
• GSC Stage 2 camshafts (Stage 3 available)
• Multi-angle valve job & final lash

Gaskets, Hardware & Accessories:

• IAG / ARP 14mm head stud set
• IAG Fire-Lock™ head gaskets
• OEM valve cover gaskets & cam seals
• OEM valve covers
• Wrist pin seal, rear main seal, and 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.