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IAG Performance S4T EJ20 Short Block Stage 4 Tuff EJ20 Subaru Closed Deck Short Block

Engine Short Block


IAG Stage 4 Tuff EJ20 Subaru Closed Deck Short Block for 02-05 WRX.

  • All IAG short blocks are balanced and blueprinted.
  • Compression Ratio: 8.5:1 on S20 Cylinder Heads (EJ20)
  • Head Gasket Required: Note: IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set PN# IAG-ENG-1745
  • The IAG Stage 4 Tuff Short Block has a power output rating of 1000BHP.
Pricing: $6,599.99

Free ground shipping on all order over $100.00 (some exclusions may apply)


Subaru: Impreza 02 - 05 WRX

  • IAG's custom pistons feature a lightweight design while increasing strength where you need it and are designed to work exclusively with the IAG +2mm Tri-Beam connecting rods. The wrist pin is short and is made from H13 tool steel and the pin piers are profiled to increase pin boss strut. IAG's pistons feature a 25% larger oil ring for reduced oil consumption and added gas ports that aid ring sealing in high boost conditions.
  • Stage 4 Tuff Closed Deck Includes: Case Halves -Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 92.5mm, Fire-Lock -IAG Fire-Lock receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subarus - IAG Fire-Lock head gaskets required, Head Studs -Machine case to fit 14mm head studs - Head studs sold separately, Pistons -IAG-Spec JE FSR 92.5mm 2618 Forged Pistons, Electroless Nickel Plated Tops & Ring area, Ring Set, .250" / .906" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins), Connecting Rods -IAG-Spec Tri-Beam +2mm w/ ARP 625+ Rod Bolts, Rod / Main Bearings -ACL or King Race bearings, Crankshaft -New Subaru 2.0L EJ20 Crankshaft with improved oil passages, Case / Main Bolts -Standard FHI Subaru case bolts.

IAG Stage 4 Tuff Subaru EJ20 Closed Deck Short Block. The IAG Stage 4 Tuff Short Block starts with brand new Subaru 2.0L 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 for our new Fire-Lock head gasket solution that is loosely derived from diesel technology where a counterbore step is machined around each cylinder bore allowing specially sized fire rings to drop into the machined area and head gasket bores. The Stage 4 Tuff case is then drilled and tapped to accept 14mm head studs that combined with the IAG Fire-Lock head gasket set greatly reduces head gasket failure during high cylinder pressure scenarios. Next, the short block is Deck Plate bored and honed to 92.5mm 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 Subaru 2.0L WRX crankshaft with improved oil passages that is matched to ACL or King race main bearings. Custom IAG TRI-BEAM +2mm connecting rods by Manley and ARP 625+ 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 (upgrading to ARP mains requires line honing). Finally, IAG-Spec 92.5mm JE FSR 2618 Forged Pistons with electroless nickel plated tops and ring area as well as upgraded .250" / .906" H13 wrist pins are added to finish the Stage 4 Plus block.


  • IAG-ENG-1455
  • IAG-ENG-1455
  • 887753780836
  • IAG Performance
  • New


Shipping Information

  • Item Requires Shipping
  • 105.0 lbs.
  • W19.0000” x H16.0000” x L19.0000”
  • Free ground shipping on all order over $100.00 (some exclusions may apply)

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