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.