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
- Pistons – IAG-Spec 99.75mm 2618 Forged Pistons w/ Extreme .210” 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 Bolts – ARP Main Bolts
- 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.
Additional Options Available:
- Head Studs - IAG / ARP Spec 14mm head studs, nuts, and washers - $550
- Head Gaskets - IAG Cooper Fire Ring .051" Head Gasket with 14mm Head Stud Provisions for high horsepower, high boost applications - $219.98 *Note specific gaskets are required for this block.
- 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).
- 14mm Head Studs, Head Gaskets, Oil Pump all sold separately, and are required to run.
- 8.5:1 on D Cylinder Heads (EJ255)
- 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
Head Gasket Recommendations:
- *IAG Cooper Fire Ring .051" Head Gasket with 14mm Head Stud Provisions for high horsepower, high boost applications
The IAG / Willall Stage X Short Block has power output rating of 1000+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