IAG 900 Closed Deck Long Block Engine w/ Stage 4 Heads & GSC S3 Cams

2006-2014 Subaru WRX / 2006-2013 Subaru Forester XT / 2007-2009 Subaru Legacy GT

Ships for free in the 48 states

SKU: IAG-ENG-4025DS3We price match!

On order from MFG
Average time to ship: 9 business days


  • Fully blueprinted, balanced, and assembled by IAG Performance
  • Designed to handle up to 900+ BHP
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IAG 900 Closed Deck Long Block Engine w/ Stage 4 Heads & GSC S3 Cams 

IAG Magnum Closed Deck Includes:

  • Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
  • IAG Fire-Lock receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subaru's - *IAG Fire-Lock head gaskets required
  • Machine Case for 14mm head studs
  • IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Electroless Nickel Plated Tops & Ring area, Ring Set, .250" / .906" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
  • IAG-Spec Tuff H-Beam +2mm / ARP 625+ Rod Bolts.
  • Rod / Main Bearings - ACL or King Race bearings.
  • New Subaru Nitride Treated 2017+ STI Crankshaft.
  • Case / Main Bolts – Standard FHI Subaru case bolts.



  • Heads - Brand New Subaru OEM WRX STI Cylinder Head Castings
  • Machine Porting - CNC Ported Intake and Exhaust Runners
  • GSC 37mm (+1mm) Intake Valves
  • Exhaust Valves - GSC 33mm (+1mm) Super Alloy Exhaust Valves
  • Springs / Retainers - Beehive Valve Springs & Retainers
  • Guides - GSC Maganese Valve Guides
  • GSC Valve Stem Seals
  • Lifters - OEM Lifter Buckets
  • Camshafts - GSC Stage 2 or Stage 3 Billet Camshafts
  • Multi-Angle Valve Job
  • Machined Cam Lobe Clearance
  • Drilled For 14mm Heads Studs
  • Resurfaced
  • Ultrasonic Cleaning
  • Final Lash



  • Head Studs - IAG / ARP 14mm Set
  • Head Gaskets - IAG Fire-Lock
  • Valve Cover Gaskets - OEM
  • Cam Seals-OEM
  • Valve Covers-OEM
  • Wrist Pin Seal, Rear Main Seal Separator Kit
  • Crankshaft Woodruff Key



For those of you with a tired EJ, or an EJ with large holes in the block that shouldn't be there, you're in luck. This particular short block has been built and assembled by one of the most established names in the Subaru performance industry, IAG Performance. This is the IAG 900 Closed Deck Long Block that has been blueprinted, balanced, and assembled to be ready to install in your Subaru. For those of you with modifications that make more horsepower and more boost, you may be surpassing the limits of the factory short block, and the IAG 900 is a great option for those of you who want an engine strong enough to sustain up to 900+ HP levels. 

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