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IAG Stage 4 Tuff EJ25 Closed Deck Case Halves O-Ringed Bored Honed 14mm Head Stud - Subaru Models (inc. 2006-2014 WRX / 2004+ STI)

IAG Stage 4 Tuff EJ25 Closed Deck Case Halves O-Ringed Bored Honed 14mm Head Stud

Subaru Models (inc. 2006-2014 WRX / 2004+ STI)

IAG Stage 4 Tuff EJ25 Closed Deck Case Halves O-Ringed Bored Honed 14mm Head Stud - Subaru Models (inc. 2006-2014 WRX / 2004+ STI)
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Part # IAG-ENG-1807
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Features & Product Details

Machined frRallySport Direct now carries highly sought-after high-performance upgrades and accessories brought to you by IAG Performance. 

On this page, you are looking at the IAG Performance Stage 4 Plus EJ25 Closed Deck Case Halves with 14mm Head Stud Conversion. These have also been bored and honed to 99.75mm.

This is one of the most cost-effective short block modifications for high-horsepower applications for those of you who aren't ready to jump into billet waters. The deck surface is machined to accept specially CNC cast inserts that strengthen the weakest point of the OEM case at the upper sleeve. 

Here are more details:

  • Deck surface is machined to accept specially CNC'd cast inserts that strengthen the weakest point of the OEM case at the upper sleeve
  • Inserts are specially machined to accept CNC threaded case bolt plugs that allow coolant to flow through and ensure that the thickest part of the plug is supporting the weakest area of the case
  • Case halves are CNC drilled and tapped to accept 1/2 inch head studs that greatly reduce head gasket failure during high cylinder pressure scenarios
  • IAG's machining process converts the semi-open deck to a complete closed deck and uses threaded plugs to provide additional support at the case bolt access positions
  • Case insert material closely matches the metallurgy of the aluminum case material in the factory block
  • IAG performs all closed deck conversions 100% in-house using a 4th axis rotary indexer in their 2015 Haas VF-4SS CNC Vertical Machining Center
  • Includes 1 IAG Stage 4 Plus Closed Deck converted EJ25 case halves
  • Machined for 9.5mm pinned mains
  • Includes ARP case bolt set
  • Line honed mains
  • Bored and honed to 99.75mm
  • Machined for 14mm head studs (head studs sold separately)
  • Includes 8 threaded case bolt plugs
  • Note: Compression ratio is subject to change based on cylinder heads and head gaskets used. 

  • 8.2:1 on B, V, and W cylinder heads (EJ257)
  • 8.5:1 on D cylinder heads (EJ255)
  • Specifications

    Brand: IAG Performance
    Assembly: Case Halves Only
    Bore Size (mm): 99.75
    Displacement: 2.5L
    Mfgr. Warranty: 12 Months / 12k Miles
    Condition: New Product
    Return Policy:
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