IAG 950 EJ25 Destroked 2.35L Closed Deck Short Block For WRX, STI, LGT, FXT - 950BHP
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IAG Performance
IAG 950 EJ25 Destroked 2.35L Closed Deck Short Block For WRX, STI, LGT, FXT - 950BHP
- SKU:
- IAG-ENG-S953
- Availability:
- Usually Ships in 3 to 4 Weeks
- Proposition 65:
- P65 WARNING: Cancer and Reproductive Harm www.P65Warnings.ca.gov.
IAG 950 EJ25 Destroked 2.35L Closed Deck Short Block For WRX, STI, LGT, FXT - 950BHP
IAG 950 EJ25 2.35L DESTROKED CLOSED DECK SHORT BLOCK FOR WRX, STI, LGT, FXT - 950 BHP
THE IAG 950 EJ25 2.35L DESTROKED CLOSED DECK SHORT BLOCK
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.
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 (Not Included) 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.
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 now 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.
What's Inside:
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
Head Gasket Required:
- *IAG Fire-Lock™ .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1741
Power Rating:
Power: The IAG 950 Short Block has a power output rating of 950 BHP
Hardware / Seal Option:
Not planning on reusing your original short block service plugs and covers? IAG offers a simple comprehensive cover and seal kit that includes (1) Rear main seal, (3) OEM wrist pin plugs, (3) OEM wrist pin plug washers, (1) OEM separator cover, (6) OEM separator cover bolts, (1) OEM wrist pin service cover, (1) OEM wrist pin service cover O-ring and (2) OEM wrist pin service cover screws. *If you are reusing your original wrist pin service plugs and covers always replace the (3) OEM wrist pin plug washers and (1) wrist pin service cover O-ring before installing a short block to avoid potential leaks. *Never reuse a rear main seal on a new short block.
Head Gasket Option:
After years of research and development testing, the IAG Performance Fire-Lock™ head gasket is the newest solution to preventing head gasket failure on high horsepower and high boost Subaru EJ25 engines. This solution 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 shims are designed to create a compression seal once the heads are installed and torqued into place. IAG fire rings are manufactured to a very strict tolerance from a proprietary alloy and are then put through a heat treatment process. The gaskets are manufactured from an asbestos-free composite raw material and feature a silicone based beading applied to critical areas to improve sealing around all water and oil passages. The combination of the alloy compression shims and gaskets assure maximum sealing for a Subaru EJ25 turbocharged engine.
*The IAG Fire-Lock™ gaskets require machine work for installation and are recommended for use with 14mm head stud hardware.
*The gaskets are sold in pairs with four Fire-Lock™ rings.
Features:
- Composite Material
- IAG-Spec Alloy Ring
- Specifically designed for 14mm Head Studs
- Silicone Beading
- 100mm Bore
- .051" Thickness
- Intended for High Horsepower, High Boost applications
- IAG ARP 14mm Head Studs Required
- Gaskets sold in pairs
Install Notes:
1. If a block or cylinder head was previously o-ringed the groove must be filled and resurfaced before using this type of gasket.
2. These gaskets require IAG ARP 14mm head studs to achieve the required torque necessary for proper installation.
3. Due to the required torque, any block that was previously honed will need to go to the next size overbore.
4. Future servicing will require cylinder head resurfacing due to an imprint left from the Fire-Lock™ rings.
Oil Pickup / Oil Baffle / Windage Tray Options:
The IAG Performance Subaru WRX / STI oil pickup was designed by Tigwerks to replace the OEM EJ25 oil pickup, which is prone to failure. It's a well-known fact that the OEM oil pickups often crack and fail which, in most cases, destroys your engine from lack of oil pressure. To avoid the cracking failures seen in the OEM oil pickup tubes, the Tigwerks oil pickup is manufactured from heavy-gauge steel tubing that is 3x thicker than OEM. Additionally, it features a flange machined from 3/8"Â 1018 CR steel to mate with the block, sealed with a Viton O-ring. The integrated heavy-duty mounting bracket uses two mounting points rather than the OEM single mounting point. Furthermore, the oil pickup features a formed bottom with an OEM style mesh screen for proper filtration. The TIG-welded oil pickup's increased material thickness, matched with the two-point heavy-duty mounting bracket, helps ensure that it does not fatigue and fail over time like an OEM unit.
The IAG Oil Control Baffle and Windage Tray System is designed to limit potential blow-by and prevent oil starvation in your Subaru's WRX / STI EJ engine during high rpm and high g-force driving. Through the use of Viton one-way flapper valves on our baffle and louvers in our windage tray, oil is prevented from reentering the upper crankcase area and is directed down into the oil pan to ensure plentiful supply to the oil pickup. IAG's integrated two-piece Oil Control Baffle and Windage Tray System is designed to work with our own oil pickup, as well as other oil pickups*. The baffle fits neatly in the engine crankcase area, allowing normal installation of the OEM oil pan and popular aftermarket pans*.
Oil Pickup & Baffle Install Notes
- EJ20 Subaru WRX engines require EJ25 oil pans for fitment
- IAG oil pickup spacer (Part# IAG-ENG-2081SP) is required when using IAG oil pickup with Killer B Oil Pan.
- *Does not work with Moroso oil pans or pickups
Oil Pump Option:
The 11mm Subaru Oil pump is one of the most popular off the shelf pumps to use on EJ25 engines. Originally equipped on the 2008-21 STI Dual AVCS engines, it provides an adequate amount of pressure and flow that fits the needs of many OE and built engines. But, as with almost anything, there is room for improvement.
Increasing oil flow volume and pressure in an EJ25 ensures that the bearings have sufficient oil film under all power levels and driving conditions. Additional oil flow to the engine provides a greater oil reserve to operate the AVCS solenoids and cam gears - giving you more consistent performance results.
The IAG Stage 2 CNC Ported 11mm oil pump was developed over years of servicing street and racing engines. In that time IAG has tested and utilized the majority of the popular Subaru oil pumps available on the market (JDM, Cosworth, ACL etc.) for customer, personal and racing vehicles.
Over the last few years if you wanted an upgraded oil pump over the stock 11mm you would either buy a hand ported model from a trusted source, or often an OEM JDM (Japanese Market) 12mm pump. We believe that we have developed a better alternative. The IAG Stage 2 CNC Ported 11mm oil pumps have shown through lab testing on a Spintron Machine that it will outperform a JDM 12mm.
- Stage 2 flows 11.1% more oil than the OEM 11mm Oil Pump
- Stage 2 flows 9% more oil than the OEM 12mm Oil Pump
- Stage 2 oil pressure is 12.4% higher than the OEM 11mm Oil Pump
- Stage 2 oil pressure is 9.8% higher than the OEM 12mm Oil Pump
The Stage 2 Oil pump is a cost effective solution that outperforms the market standards. This pump has been extensively tested on street cars, track cars, and on our in-house Spintron to ensure consistent and repeatable performance.
Each IAG Stage 2 oil pump starts life as an OEM spec 11mm oil pump, straight from Subaru. IAG completely disassembles the new oil pump including pulling the rotors, backing plate & pressure relief valve. Next, the main body is fixtured in our in-house 5-Axis Centroid CNC machine where the inlet and outlet passageways are CNC ported. This allows for a larger, more consistent pathway for the oil into and out of the gerotor internals and helps to prevent cavitation. The Oil Pump Outlet where it meets the engine block is also CNC “Port Matched”, for a perfect transition into the engine block. The Inlet and Outlet sides of the gerotor are also opened up on the CNC mill to reduce inlet side cavitation, and to reduce outlet side pressure drops.
The pressure relief valve piston is REM Polished, which provides a non-directional, low Ra, polished finish. This reduces friction, heat and possibility of the relief valve piston galling and sticking, a common failure point on the OEM pumps.
The piston is reinstalled and confirmed to operate correctly. The rotors are measured and checked to be within the manufacturer's specification - aka Blueprinted, and installed next. The pump is then put together with a light coating of assembly lube to reduce friction and scuffing and aid in priming on first start up.
Finally, the backing plate is installed. Loctite is added to the hardware, and each piece receives a painted mark after it is correctly torqued. The pump ships ready to install, with all hardware and seals required for installation.
Installation Instructions:
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
Need Help Choosing a Block?
Our Experts Are Here to Help
We made this video to highlight the differences between each of our short blocks and to help you choose the best one for your performance goals and budget. Our Build Advisors and Customer Support staff can also assist you with any questions or concerns. Just click the button below for assistance.
Quality Guaranteed
Available 24 Month/24,000 Mile Warranty*
We stand behind every hand-built engine we produce. IAG's Standard Short Block Workmanship Warranty covers your short block for 12 months or 12,000 miles. We have also teamed up with a selection of IAG Certified Installation Facilities which offer up to a 24 month/24,000 mile workmanship warranty when the engine is purchased, installed, and tuned by that IAG Certified Installer.
Model Year & Fitment
- 2002 Subaru WRX
- 2003 Subaru WRX
- 2004 Subaru WRX
- 2005 Subaru WRX
SHIPPING
FREE SHIPPING on orders of $250 or more* Simply look for the logo to enjoy free shipping on selected items throughout the store. Oversized packages and freight shipments do not qualify for free shipping. If the items in your order which qualify for 'Free Shipping' total $250 or more, your order ships FREE! Free shipping is only available to the continental United States also referred to as the “lower 48 states”.Shipping Policy: All products sold on the shopping cart are shipped by UPS or USPS. All packages include shipping insurance in case they are lost or damaged. USPS requires signature confirmation on all insured orders over $200.00. USPS shipping times are estimated and not guaranteed. UPS tracking numbers are automatically generated when a package ships and the number is sent to the email address you provided. If a package contents is damaged during shipping please notify the shipping driver and file a claim with the shipper. You have 14 days to inspect your shipment and contents. After that period of time, IAG is no longer responsible for missing items. You have 30 days to report any damaged or incorrect items, after that period of time IAG is no longer responsible for returns or exchanges. You can contact us by Email or call 410-840-3555 for assistance. *International orders are subject to customs charges, duties or fees. Please check with your local customs office before ordering. IAG is not responsible for international customs charges, duties or brokerage fees.
Drop Shipping: Some items require drop shipping to complete an order. These products are shipped from manufacturer or distributor warehouses across the country. In some cases, this may speed up delivery time. In other cases, it could add 1-3 days to the delivery time. If you have a question regarding an order please contact our sales desk at 410-840-3555.
Order Processing: Orders placed after 3PM EST may not be processed the same day. Order processing may take 24-48 hours. USPS orders placed after 10am EST will ship the following business day if the items are in stock
RETURNS
How do I return an item?
You have 14 days to inspect your shipment and contents. After that period, IAG is no longer responsible for missing items. You have 30 days to report any damaged or incorrect items, after that period IAG is no longer responsible for returns or exchanges. All stocking products are subject to a 30 Day return policy. The item(s), when approved for return, are subject to a 20 percent restocking fee. Canceled orders may be subject to a 20 percent cancellation fee. All product returns require a return authorization number before being shipped back to IAG or the manufacturer. An “RMA” number is obtained by calling the IAG Support Desk at 410-840-3555 or emailing support@iagperformance.com. Some products may require shipping back to the manufacturer for inspection before a return or exchange may be processed. Some products may not be able to be returned. Products that have been modified or installed are not eligible for return. There are no returns or cancellations for Special Order/Made to Order items and Electrical Components (including the COBB Accessport). Items returned after the 30 Day return period without an RMA will be refused. Canceled service appointments with deposits are non-refundable.
Refunds take 30 days or less. Payments made by Credit Card or PayPal are returned back to the original account used during the transaction. There are no cash returns; we will issue a business check for the return of funds. Refunds are decided by the management and not by sales staff. Canceled service appointments with deposits are non-refundable.
IAG Performance Product Warranty (Excluding - Short Blocks / Long Blocks)
This limited warranty gives you specific legal rights and you may also have other rights, which vary from state to state. We limit the duration and remedies of all implied warranties, including, without limitation, the warranties of merchantability and fitness for a particular purpose to the duration of this express limited warranty. Some states do not allow limitations on how long an implied warranty lasts. The remedies described below are your sole and exclusive remedies and our entire liability for any breach of this limited warranty. Our liability shall under no circumstances exceed the actual amount paid by you for the product, nor shall we under any circumstances be liable for any consequential, incidental, special or punitive damages or losses, whether direct or indirect.
This warranty covers defects in materials and workmanship of your IAG Performance Product for 12 Months or 12,000 Miles from the date of receipt.
IAG will repair any IAG Manufactured Product that proves to be defective in materials or workmanship within the warranty period. If a repair is not possible, we will either replace your Product with a new Product of similar composition and price, or refund the full purchase price of your Product, at our sole discretion. There is no charge for inspection but the buyer is responsible for shipping charges.
IAG Performance Engine Warranty
For more information concerning our engine warranty please visit IAG Performance Engine Warranty Page
Other Manufacturer Products:
Products not manufactured by IAG are subject to the individual manufacturer warranties which may apply. If you have questions concerning the fitment, appearance, or performance of your item, please contact a member of our customer support team for assistance.
Our customer service team is happy to assist you with the products purchased from IAG Performance. Our support associates can help you with installation support, troubleshooting advice, and help to identify possible manufacturer defects.
For products that are found to have defects, our support department can provide the contact information for the manufacturer to arrange a warranty inspection and, if applicable, any necessary repairs or replacement shipments.
You may also contact the manufacturer directly for information regarding product eligibility and specific terms and conditions of warranty coverage.