IAG Stage 2.5 Subaru EJ25 Closed Deck Short Block
The IAG Stage 2.5 Short Block starts with brand new Subaru 2.5L engine case halves. IAG machines the case halves assembled together in our Haas VF-4SS CNC mill 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. Next, the short block is Deck Plate bored and honed to 99.75mm in our in-house Sunnen SV-10. 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 new 2017+ Subaru 2.5L nitride treated STI crankshaft that is matched to ACL or King race main bearings. IAG Spec H-Beam connecting rods and ARP rod bolts are utilized along with ACL or King race rod bearings. The case halves are sealed with new OEM main/case bolts and sealant (upgrading to ARP mains requires line honing). Finally, your choice of Manley Spec 99.75mm Platinum Forged Pistons or Cosworth 99.75mm Forged Pistons to finish the Stage 2.5 short block.
Stage 2.5 Closed Deck Includes:
- Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
- Pistons - Manley 99.75mm Platinum Forged Pistons / .210" wall wrist pins
- Connecting Rods - IAG Spec H-Beam / ARP2000 Rod Bolts.
- Rod / Main Bearings - ACL or King Race bearings.
- Crankshaft - Standard New Subaru Nitride Treated 2017+ STI Crankshaft.
- Case / Main Bolts – Standard FHI Subaru case bolts.
Additional Options Available:
- Pistons - Cosworth 99.75mm Forged Pistons with Cosworth .210" Wrist Pins - $300
- Oil Pump - Subaru JDM 12mm High Volume Oil Pump - $219 or 11mm Subaru Oil Pump - $194.95
- Rod Bolts- 625+ ARP rod bolts - $250
- Wrist Pins - Upgrade Manley Pistons to Extreme .250" thick-wall wrist pins - $100
- Head Gaskets - JE Pro Seal .039 inch Head Gaskets - $96 or Cosworth 1.1mm Head Gaskets- $158
- Hardware / Seal Option - $105.99 (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 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 Stage 2.5 Short Block has power output rating of 700BHP.
*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 After Sale Document - Contains Shipping, Engine Care and Warranty Information