IAG 950 Closed Deck 2.35L Destroked Long Block Engine w/Race Heads

IAG 950 2.35L DESTROKED LONG BLOCK ENGINE WITH IAG 950 RACE HEADS FOR 01-14 WRX, 01-21 STI, 03-13 FXT, 04-09 LGT 

POWER RATING

The IAG 950 Destroked Long Block has a power output rating of 950BHP and maxiumum of 8,500 RPM.

DROP IN AND DRIVE

The IAG Performance hand-built Subaru 950 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 950 Cylinder Head packages, along with a full range of carefully selected high-performance components to complete the assembly. 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 950 2.35L Destroked Long Block Engine package delivers track-level power, making it ideal for high-performance applications that support up to 950 BHP. This comprehensive Long Block package features our IAG 950 Closed Deck Short Block that utilizes a brand new Subaru EJ25 engine case that is converted to closed deck and is bored and honed to 99.75mm. The IAG 950 2.35L block features 14mm head stud machining, as well as our Fire-Lock™ 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 combination of the alloy compression shims and gaskets assure maximum sealing for Subaru EJ25 turbocharged engines. The IAG 950 internals include custom JE 99.75mm FSR 2618 pistons, JE Pro Seal Ring Set, along with .240" H13 tool steel wrist pins. Also included are custom IAG spec +2mm H-beam forged connecting rods with 625+ rod bolts, 2.0L FHI crankshaft, ACL Race Bearings and Standard FHI Subaru case bolts.

The block is then paired up with our IAG 950 Fully CNC Ported Cylinder Heads to deliver maximum flow for high horsepower applications. The heads start as brand new Subaru OEM cylinder head castings that are CNC machined and resurfaced. The heads are outfitted with GSC valve train components, consisting of +1mm oversized intake and SuperAlloy exhaust valves, IAG Beehive Springs, as well as GSC Billet Stage 2 camshafts and Kelford DLC coated buckets. To complete the package, we add an IAG / ARP 14mm head stud set and all the required gaskets for the final valve cover-to-valve cover assembly.

IAG 950 EJ25 2.5L CLOSED DECK SUBARU SHORT BLOCK

THE ULTIMATE WEEKEND RACER

IAG’s 950 EJ25 2.35 L 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.

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. This results in improved combustion efficiency and reduced stress on engine components at high RPMs. 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.
Destroked for High-reving Applications

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.

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 hold the assembly together.

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.

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 for 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.

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.

FORGED ALUMINUM ALLOY

The OEM EJ25 pistons continue to be produced using a hypereutectic cast design. This casting method is susceptible to irregularities in both the casting process and the materials used, leading to potential weaknesses in the pistons. This is where our custom JE pistons come in; forged from a durable 2618 T6 Alloy with a unique silicone additive, these JE pistons effectively absorb the direct shock and impact of combustion. Engineered to withstand ringland damage due to detonation and preignition, they feature a higher strength material and have been custom designed to feature thicker ringlands.

IAG 950 CNC PORTED RACE CYLINDER HEADS PACKAGE

BUILT WITH RACING IN MIND

The IAG 950 CNC Ported Race Cylinder Heads are designed for racing and competition. These fully CNC ported heads provide a significant upgrade in flow over the IAG 750 heads. These heads work great for cars where getting more power might be the difference between winning or losing that big race. The IAG 950 heads work great for drag racing, as well as high horsepower time attack or hill climb, and are designed to support up to 950 BHP with supporting mods. These heads include upgraded GSC +1MM Superalloy Valves, GSC Viton Valve Stem Seals, Upgraded GSC Valve Guides, IAG-Spec Beehive Valve Springs with Titanium Retainers, and OEM Keepers. GSC S2 Camshafts are matched to Kelford DLC coated valve lifter buckets. We also offer an optional chamber modification service for EJ20 heads to allow use on EJ25 short blocks

THE 950 PORTED HEAD PACKAGE

Each IAG 950 Cylinder Head Set starts with new OEM castings from Subaru of America. The first step is to select your Year and Model of vehicle so that we may provide you with the right castings to fit your project. Next, you'll select whether or not you want to include our optional GSC camshaft package. If selected, these heads will include new GSC S2 Camshafts and Kelford DLC Coated Lifter Buckets for valve adjustment.

This IAG 950 fully CNC ported head package starts with brand new WRX STI OEM head castings directly from Subaru of America. The bare castings are visually inspected then fixtured into our in-house Centroid 5-axis CNC Machine. The Centroid CNC ports the intake and hard to reach exhaust "dog-leg" port runner. The benefit of CNC porting is not only an efficient way of machining the heads, it also offers consistent port results that are hard to achieve by hand. Once the Centroid completes the port process the heads undergo a cam clearance machining process that removes material from the lifter area where large duration cam profiles are known to contact the castings. Shortly after the heads are drilled to fit larger 1/2" or 14mm head studs, which are commonly used in high horsepower builds. Next, the OEM guides are pressed out and replaced in favor of GSC Manganese-Bronze valve guides that are shaped to improve airflow. Once all the new intake and exhaust guides are in place they are diamond-honed in our honing station. The heads are then fixtured in our Newen 3.0 Valve Guide and Seat Machine to cut all intake and exhaust seats with a multi-angle valve job that suits the flow characteristics of GSC's +1mm valves. At this point, the heads' decks are resurfaced using our TS-3000 BlockMate which cuts the aluminum to a smooth even finish. Next, the heads are ultrasonically cleaned to remove debris and oils from the machining process. Finally, the heads are reassembled using IAG-Spec Beehive Valve Springs and Retainers along with GSC Viton stem seals.

WHAT MAKES CNC PORTING BETTER?

Cylinder head porting has been around since the invention of the internal combustion engine. It can be done by hand with a die grinder and some cartridge rolls, and a seasoned professional can likely get a good result that way. Unfortunately, doing porting this way requires a lot of experience and care. One slip of the die grinder can ruin your cylinder head. This is where CNC porting comes in. Using our Centroid 5 axis CNC porting machine we can achieve the same results every time we put a set of heads into the machine. Every cylinder head comes out exactly the same and uses our race-proven, computer controlled, CNC porting program to guarantee results.

GSC S2 CAMSHAFT AND LIFTER BUCKET PACKAGE

To get the most out of these heads we selected the GSC Power-Division billet S2 camshafts for your IAG 950 Head Package. These cams are built to suit the higher horsepower these heads will support. With a power range of 500 WHP and up, you need some additional supporting mods to utilize the true potential of the S2s. Our IAG 950 Short Block, an upgraded turbocharger and fuel system, and a quality engine management system are key. Along with the camshafts we'll include all new Kelford DLC Coated valve lifter buckets and set final lash.

QUALITY GURANTEED

We stand behind every hand-built engine we produce. IAG's Standard Long Block Workmanship Warranty covers your long block for 12 months or 12,000 miles.

Vehicle Fitment:

Additional hardware may be required to install this long block to the following vehicles, including but no limited to ECU, Sensors, Ancillaries, Covers, Pumps etc.

• 1999-2014 Subaru WRX
• 1999-2021 Subaru STI
• 1997-2013 Subaru Forester XT
• 2004-2009 Subaru Liberty GT
• 2004-2009 Subaru Outback XT

• IAG 950 EJ25 2.35L LONG BLOCK INCLUDES
• IAG 950 EJ25 2.35L Short Block Includes:
• 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 Subaru's - *IAG Fire-Lock™ head gaskets required
• Head Studs - Machine Case for 14mm head studs - *Head studs are 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 and 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: All Calculated with Fire-Lock Gaskets
• 9.2:1 on D Cylinder Heads (EJ255)
• 8.8:1 on B, V, and W EJ257 Heads
• IAG 950 CNC Ported Cylinder Heads:
• Heads - Brand New Subaru OEM WRX STI Cylinder Head Castings
• Machine Porting - IAG CNC Ported Intake and Exhaust Runners
• Intake Valves - GSC 37mm (+1mm) Intake Valves
• Exhaust Valves - GSC 33mm (+1mm) SuperAlloy Exhaust Valves
• Springs / Retainers - IAG-Spec Beehive Valve Springs & Retainers
• Guides - GSC Maganese 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 Heads Studs
• Resurface
• Ultrasonic Cleaning
• Final Lash
• 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 review the PDF document below regarding installation, break-in procedures and warranty information.

PDF After Sale Document - Contains Shipping, Engine Care and Warranty Information

Additional hardware may be required to install this long block to the following vehicles, including but no limited to ECU, Sensors, Ancillaries, Covers, Pumps etc.