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IAG Stage Magnum EJ25 Subaru Closed Deck Short Block - WRX/STI/FXT/LGT

The IAG Stage 2.7 Magnum 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 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 2.7 Magnum 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 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. IAG-Spec Tuff H-Beam +2mm connecting rods 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 99.75mm 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 2.7 Magnum short block. Additionally, all IAG-Spec piston skirts utilize the JE Perfect Skirt coating. 

Stage 2.7 Magnum Closed Deck Includes:
  • Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
  • Fire-Lock - 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
  • Head Studs - Machine Case for 14mm head studs - *Head studs are sold separately
  • Pistons - 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)
  • Connecting Rods - IAG-Spec Tuff H-Beam +2mm / ARP 625+ 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.
Additional Options Available:
  • Head Studs - IAG / ARP 14mm head studs, nuts, and washers - $550
  • Oil Pump - Subaru JDM 12mm High Volume Oil Pump - $219 or 11mm Subaru Oil Pump - $199.95
  • Head Gaskets - IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* Required for use with this short block -$249.99
  • Hardware / Seal Option - $105.99 (Wrist pin plugs, washers, separator cover, bolts, etc. In case you don’t want to transfer from the original engine).
Compression Ratio:
  • 8.5:1 on D Cylinder Heads (EJ255)
  • 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
Head Gasket Required:
  • *IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1740
Power: The IAG Stage 2.7 Magnum Short Block has a power output rating of 850BHP.

*All IAG short blocks are balanced and blueprinted.



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