IAG Stage 4 Extreme 2.5L Subaru Closed Deck Short Block For WRX, STI, LGT, FXT
IAG Stage 4 Extreme Closed Deck EJ25 Subaru Short Block
The IAG Stage 4 Extreme 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 in our Haas VF-4SS CNC mill 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 Stage 4 Extreme 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 our in-house Sunnen SV-30 the most advanced automotive cylinder hone available. IAG's in-house honing process is able to set custom piston to wall clearances to best fit your needs. The modified case halves are then assembled using a IAG Billet crankshaft by Callies that is matched to ACL or King race main bearings. Custom IAG TRI-BEAM +2mm connecting rods by Manley and 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. IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins with electroless nickel plated tops and ring area are chosen to finish the Stage 4 Extreme short block. 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 strut. Finally, IAG's pistons feature a 25% larger oil ring for reduced oil consumption and added gas ports that aid ring sealing in high boost conditions.
Stage 4 Extreme Closed Deck Includes:
- Case Halves - Converted to Closed Deck from brand new OEM Subaru case halves, bored and honed to 99.75mm.
- Pinned Mains - Machine case for 9.5mm pinned mains and lined 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" / .927" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
- Connecting Rods - IAG-Spec Tri-Beam Connecting Rods with ARP 625+ Rod Bolts.
- Rod / Main Bearings - ACL or King Race Bearings.
- Crank - Billet Crank by Callies
- Case / Main Bolts - ARP Main Bolts.
Additional Options Available:
- Head Studs - IAG / ARP Spec 14mm head studs, nuts, and washers
- Head Gaskets - IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* Required for use with this short block
- Oil Pump - Subaru JDM 12mm High Volume Oil Pump or 11mm Subaru Oil Pump
- IAG Oil Pickup - Upgraded oil pickup featuring heavy gauge steel tubing, 2 point bracket & mesh filter
- IAG Oil Baffle - Upgraded oil control baffle and windage tray
- IAG Oil Pickup & Baffle Set - Upgraded oil pickup, oil control baffle, and windage tray
- Hardware / Seal Option - (Includes: Wrist pin plugs, washers, separator cover, bolts, etc. In case you don't want to transfer from the original engine).
- 8.5:1 on D Cylinder Heads (EJ255)
- 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
Head Gasket Required:
- *IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1740
Power: The IAG Stage 4 Extreme Short Block has a power output rating of 1100BHP.
*All IAG short blocks are balanced and blueprinted.
Oil Pickup / Oil Control Baffle / Windage Tray Options:
The IAG Performance Subaru WRX / STI oil pickup is designed 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 oil pickup is manufactured from heavy-gauge steel tubing that is 2x thicker than OEM. Additionally, it features a flange machined from 3/8" stainless 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
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.
Please review the PDF document below regarding installation, break-in procedures and warranty information.
PDF Closed Deck Install Guide for 1/2" & 14mm Head Studs
PDF After Sale Document - Contains Shipping, Engine Care and Warranty Information
Model Year & Fitment
- 2002 Subaru WRX (Requires Mods)
- 2003 Subaru WRX (Requires Mods)
- 2004 Subaru WRX (Requires Mods)
- 2005 Subaru WRX (Requires Mods)
- 2006 Subaru WRX
- 2007 Subaru WRX
- 2008 Subaru WRX
- 2009 Subaru WRX
- 2010 Subaru WRX
- 2011 Subaru WRX
- 2012 Subaru WRX
- 2013 Subaru WRX
- 2014 Subaru WRX
- 2004 Subaru STI
- 2005 Subaru STI
- 2006 Subaru STI
- 2007 Subaru STI
- 2008 Subaru STI
- 2009 Subaru STI
- 2010 Subaru STI
- 2011 Subaru STI
- 2012 Subaru STI
- 2013 Subaru STI
- 2014 Subaru STI
- 2015 Subaru STI
- 2016 Subaru STI
- 2017 Subaru STI
- 2018 Subaru STI
- 2019 Subaru STI
- 2020 Subaru STI
- 2005 Subaru Legacy GT
- 2006 Subaru Legacy GT
- 2007 Subaru Legacy GT
- 2008 Subaru Legacy GT
- 2009 Subaru Legacy GT
- 2004 Subaru Forester XT
- 2005 Subaru Forester XT
- 2006 Subaru Forester XT
- 2007 Subaru Forester XT
- 2008 Subaru Forester XT
- 2009 Subaru Forester XT
- 2010 Subaru Forester XT
- 2011 Subaru Forester XT
- 2012 Subaru Forester XT
- 2013 Subaru Forester XT
SHIPPINGFREE 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
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 firstname.lastname@example.org. 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.
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