IAG / Willall Stage X Billet Aluminum EJ25 Subaru Short Block
Using the same world-leading technology found in Willall’s incredible billet GT-R block, the billet EJ case seeks to change the Subaru performance tuning market by reinventing the EJ and addressing virtually every weakness that exists in max-power builds. The Stage “X” Block is a complete short block built on the Willall billet platform, which also includes pistons, rods, bearings, crank, bore/hone, case bolts, line hone, and final assembly and blueprinting.
Stage X Billet EJ25 Case Features:
- Machined from solid billet 6061-T6 Aerospace grade aluminum
- Darton Ductile iron sleeves
- Increased material thickness in all known weak points (around head studs, bottom end location)
- Unique 4 bolt bottom end strengthening
- Threads are rolled into the block rather than conventionally cut for much greater strength
- Full cooling system operation
- Radiused coolant and oil galleries for improved flow and less foaming/turbulence
- Fits all factory engine bay ancillaries (i.e. AC/PS/etc.)
- Multiple Times stiffer and stronger than the stock case
- Precision machined for a superior surface finish
- Hard anodized to avoid marking or straining
IAG Stage X Complete Shortblock Includes:
- Case - WREJBB Billet / Sleeved 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
- Machining - Machined for 14mm Head Studs *(Studs sold separately / Note the proper head gaskets or head gasket modifications are required for proper fitment with 14mm studs.
- Pistons – IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Electro-nickel Plated Tops & Ring area, Ring Set, .250" / .927" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
- Connecting Rods – IAG-Spec +2mm Tri-Beam w/ ARP625+ Rod Bolts
- Rod/Main Bearings – ACL/King Race Bearings
- Crankshaft – Manley Billet Crank
- Case / Main Bolts – ARP Main Bolts
Additional Options Available:
- Head Studs - IAG / ARP Spec 14mm head studs, nuts, and washers - $550
- Oil Pumps - Subaru JDM 12mm Oil Pump - $219 / OEM Subaru 11mm Oil Pump - $199.95
- Hardware / Seal Option - $105.99 (Includes: Wrist pin plugs, washers, separator cover, bolts, etc. In case you don’t want to transfer from the original engine).
- *IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1740
- 14mm Head Studs
- 8.5:1 on D Cylinder Heads (EJ255)
- 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
The IAG / Willall Stage X Short Block has a power output rating of 1100+BHP.
*All IAG short blocks are balanced and blueprinted.
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 O-Ring Install Guide
PDF Closed Deck Install Guide for 1/2" & 14mm Head Studs
PDF After Sale Document - Contains Shipping, Engine Care and Warranty Information
WARNING: This product can expose you to chemicals which is known to the State of California to cause cancer and reproductive harm. For more information, visit www.P65Warnings.ca.gov.