IAG Stage 3 EJ25 Closed Deck Block
£2,999.99
IAG Stage 3 closed deck converted case halves for the Subaru EJ25 engine, using CNC-machined cast inserts to strengthen the factory semi-open deck at the top of the cylinder sleeves. Supplied as a new EJ25 case machined to accept a 99.75mm overbore; bore and hone required before assembly.
SKU: RCM2996
EKS Fitment Advice
EKS currently identifies this product as Shared / Application Fitment
Compatibility of any product, greatly depends on model + year + trim + mods. Most Subaru’s are in different states of tune, so please contact Rich, from EKS to get clarity before purchasing.
Potential Applications
Subaru Impreza 1992-2000 (GC/GF), Subaru Impreza 2001-2002 (GD/GG Bugeye), Subaru Impreza 2003-2005 (GD/GG Blobeye), Subaru Impreza 2006-2007 (GD/GG Hawkeye), Subaru Impreza / WRX STI 2008-2013 (GR/GV), Subaru WRX STI 2014-2021 (VA/VAB), Subaru Forester 1996-2002 (SF), Subaru Forester 2003-2005 (SG early), Subaru Forester 2006-2007 (SG facelift), Subaru Forester 2008-2013 (SH), Subaru Legacy 1992-2003, Subaru Legacy 2003-2009 (BL/BP), Subaru Legacy 2009-2014 (BM/BR)
Full List of EKS Fitment Evidence Types
For context, here are all categories of fitment according to EKS.
- Direct Fitment: means the product is currently listed as fitting the model/generation shown.
- Shared / Application Fitment: means the product may suit shared Subaru platforms, engines, turbos, drivetrains, brakes, cooling/intake setups or modified applications.
- Universal / Service Item: means the product is broadly useful for Subaru servicing, maintenance, workshop use or general ownership.
- Needs Confirmation: means the product appears relevant, but final fitment may depend on extra details.
Product Description
The factory Subaru EJ25 case uses a semi-open (semi-closed) deck, with three narrow supports tying the case to the tops of the cylinder sleeves. This is stronger than the fully open EJ20 deck, but the top of the sleeve remains a weak point under high horsepower.
IAG’s Stage 3 Closed Deck conversion machines the deck to accept CNC’d cast inserts, closing the deck and reinforcing this area. The insert material is matched to the case’s aluminium alloy so the two expand and contract at similar rates. Outer inserts are machined from 3/4″ cast material to a finished 1/2″ thickness, and inner inserts from 1″ cast material to a finished 3/4″ thickness. The conversion is carried out on a new OEM EJ25 case using CNC machining.
This listing is for one set of IAG Stage 3 closed deck converted case halves, based on a brand new EJ25 case with a stock 99.5mm bore. Bore and hone work is required before final assembly; IAG recommends an overbore to 99.75mm.
IAG recommends line honing the case when fitting ARP case bolts, to remove any distortion introduced by the hardware. IAG installs ARP case bolts using 30W engine oil and OEM Subaru torque specifications; using other torque specs or lubricants may lead to case distortion damage.
Suitable for street or race use. Please contact Scooby Upgrades to confirm compatibility with your specific engine build before ordering.