IAG Stage 3 Extreme Closed Deck Short Block (10.5:1 Compression Ratio) – FRS/BRZ/86

Code: IAG-ENG-1323


In Stock


IAG Stage 3 Extreme FA20 Closed Deck Short Block

The IAG Stage 3 Extreme short block starts with new Subaru FA 2.0L BRZ engine case halves that are machined for improved oiling. Then 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 1/2″ head studs that greatly reduce head gasket failure during high cylinder pressure scenarios. Next, the short block is Deck Plate bored and honed that to 86.25mm on our in-house Sunnen SV-30 the most advanced automotive cylinder hone available. IAG‘s in-house honing process is able to set piston to wall clearances tighter for a quieter running engine. The modified case halves are then measured and assembled using a new FA20 WRX / BRZ Subaru crankshaft that is matched to King main bearings. Manley I-Beam rods with ARP2000 rod bolts are utilized along with King or ACL rod bearings. The case halves are sealed with new OEM case bolts and sealant. Finally, lower compression IAG-Spec 86.25mm 10.5:1 compression ratio forged pistons are spec’d and installed along with an OEM oil plug finishing off the short block. The lower compression ratio is good for BRZ / FR-S forced induction conversion applications.

Stage 3 Extreme FA20 Includes:

  • Case Halves – Converted to Closed Deck using brand new Subaru OEM case halves
  • Case Machining – Modified for improved oiling
  • Case Machining – Bored and honed to 86.25mm
  • O-Ringing – Machine and O-Ring Deck Surface
  • Head Studs – Machine Case for 1/2″ head studs – *Head studs are sold separately.
  • Pistons – IAG-Spec 86.25mm 10.5:1 Forged Pistons, Ring Set, and 1.50″ x 2.250″ Chromoly Wrist Pins
  • Connecting Rods – Manley I-Beam / ARP2000 Rod Bolts
  • Rod Bearings – ACL or KING XPG
  • Main Bearings – King XPG
  • Crankshaft – New Subaru FA20 WRX / BRZ crankshaft
  • Case / Main Bolts – Standard Subaru case bolts
  • Hardware – OEM Oil Plug – preinstalled at the oil pan location.

Additional Options Available:

  • Oil Plugs & Rear Main Seal (x2) 11024AA141 Plug, (x1) 806792010 Rear Main Seal – $40.50
  • Head Studs – IAG Performance 1/2″ head stud set manufactured by ARP – $524.99

Compression Ratio:

  • 10.5:1 (2.0 lower than stock compression) on standard gasket thickness.

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

*All IAG Short Blocks are balanced and blueprinted. This short block features a lower compression and is intended for forced induction applications.

Additional information




Head studs


Seal kit





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