IAG Stage 3 Plus Subaru EJ25 Closed Deck Short Block 

The IAG Stage 3 Plus 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 2012+ Subaru 2.5L heat-treated STI crankshaft (or Manley Billet add $1300) that is matched to ACL or King race main bearings. Manley Turbo Tuff I-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 (upgrade to ARP mains a la carte). Manley Spec 99.75mm Turbo Tuff Forged Pistons are chosen to finish the Stage 3 short block. 

Stage 3 Plus Closed Deck Includes:
Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
Pistons - Manley Spec 99.75mm Turbo Tuff Forged Pistons / .170 inch wall tool steel wrist pins
Connecting Rods - Manley Turbo Tuff I-Beam / ARP2000 Rod Bolts.
Rod / Main Bearings - ACL or King Race bearings.
Crankshaft - Standard New Subaru Heat-Treated 2012+ STI Crankshaft.
Case / Main Bolts – Standard FHI Subaru case bolts.

Additional Options Available:
Oil Pump - ACL Orbit High Volume Oil Pump - $249 or 11mm Subaru Oil Pump - $194.95
Wrist Pins - Extreme .210 inch 9310 thick-wall wrist pins - $100
Rod Bolts - 625+ ARP Rod Bolts - $200
Head Gaskets - JE Pro Seal .039 inch Head Gaskets - $96 or Cosworth 1.1mm Head Gaskets- $158
Hardware / Seal Option - $99.99 (Wrist pin plugs, washers, separator cover, bolts, etc. In case you don’t want to transfer from the original engine).

Compression Ratio:
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 3 Plus Short Block has power output rating of 900BHP.

*All IAG short blocks are balanced and blueprinted.