IAG Performance

IAG-ENG-1354

IAG STAGE 3 EXTREME EJ25 SUBARU CLOSED DECK SHORT BLOCK FOR WRX, STI, LGT, FXT


AG Stage 3 Extreme Subaru EJ25 Closed Deck Short Block

The IAG Stage 3 Extreme 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. The case halves are then CNC machined with o-ring receiver grooves around the bore surface as well as drilled and tapped to accept larger 1/2" head studs that aids in preventing cylinder heads from lifting in high boost applications. Next, the short block is Deck Plate bored and honed to 99.75mm in our in-house Sunnen SV-30 the most advanced automotive cylinder hone available. 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. Manley Turbo Tuff Tri-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 and line hone service a la carte). IAG-Spec JE FSR 99.75mm Forged Pistons are chosen to finish the Stage 3 Extreme short block. 

Stage 3 Extreme Closed Deck Includes:
  • Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
  • O-Ringing - Machine and O-Ringed Deck Surface
  • Head Studs - Machine case to fit 1/2" head studs - *Head studs sold separately
  • Pistons - IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Ring Set, .180" Chromoly wrist pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
  • Connecting Rods - Manley Turbo Tuff Tri-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:
  • Head Studs - IAG Performance 1/2" head stud set manufactured by ARP - $499.99
  • Oil Pump - Subaru JDM 12mm High Volume Oil Pump - $219 or 11mm Subaru Oil Pump - $199.95
  • IAG Oil Pickup - Upgraded oil pickup featuring heavy gauge steel tubing, 2 point bracket & mesh filter - $129.99
  • Head Gaskets - JE Pro Seal .039" Head Gaskets - (PN# SB1001-039 for D25 & B25 Heads, PN# SB1003-039 for V25, W25 & N25 Heads)
  • 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).

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
  • JE PN# SB1001-039 are for use with S20, B25 & D25 Cylinder Head Castings (2004-06 STI, 06-14 WRX, 04-13 FXT, 05-12 LGT, 02-05 WRX)
  • JE PN# SB1003-039 are for use with V25, W25 & N25 Cylinder Head Casting (2007-19 STI)


Power: The IAG Stage 3 Extreme Short Block has a power output rating of 800BHP.

Fitment-
2002-2005 WRX (Requires Mods)
2006-2014 WRX
2004+ STI
2005-2009 Legacy GT
2004-2013 Forester XT

*All IAG short blocks are balanced and blueprinted.

*Picture used for marketing purposes only, actual product may vary 

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