IAG Stage 3 Extreme EJ25 Subaru Closed Deck Short Block For WRX, STI, LGT, FXT
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.
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.
*All IAG short blocks are balanced and blueprinted.
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.
Model Year & Fitment
2002-2005 Subaru WRX (Requires Mods)
2006-2014 Subaru WRX
2004-2018 Subaru STI
2005-2009 Subaru Legacy GT
2004-2013 Subaru Forester XT
This product can expose you to chemicals including Lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov