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, o-rings, 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 stock case
- Precision machined for 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
- O-Ring – Deck surface o-ringed
- 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 / JE Proseal .039in Head Gaskets with 14mm Head Stud Provisions - (1 Pair) $159.98, Cosworth Head Gaskets modified for 14mm Head Studs (1 Pair) - $225 *Note specific gaskets are required for this block.
- Oil Pumps - ACL / Orbit Oil Pump - $229 / Cosworth 11mm Oil Pump - $599 / OEM Subaru 11mm Oil Pump - $194.95
- 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 Recommends JE Pro Seal .039 inch head gaskets for B and D casting cylinder heads.
- *IAG Recommends Cosworth 1.1mm head gaskets for all V and W casting cylinder heads.
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.
Optional Shipping Methods:
Red Carpet Service - IAG Pelican Case (Recommended):
Red Carpet Service / IAG Pelican Cases are a premium shipping option offered by IAG. Your IAG short block is shipped via a returnable polypropylene military grade IAG Pelican case, which provides optimal protection while in transit. Please contact an IAG sales associate at (410)-840-3555 within 2 business days of your purchase to provide credit card confirmation and approval for Pelican shipping - further details and logistics are explained in our Post Sale PDF document, which can be found below. The IAG Pelican case must simply be returned to IAG within 7 days of the receipt of your engine and carries no additional cost vs. cardboard box shipping. If the case is not returned in the required timeline, a core charge of $399 is placed on your card.
Blocks can alternatively be sent in a standard cardboard box, but bear a greater risk of damage in transit. While cost is the same, we suggest a Pelican case that ensures safe transit.
Please review the PDF document below regarding installation, break-in procedures, warranty information, and our Pelican Case Shipping Service. After ordering your block, please call our sales team at 410-840-3555 to approve Pelican shipping and secure the safest shipping method in the aftermarket!
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