The IAG Stage 2.5 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. 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 connecting rods and ARP 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 .180" Chromoly Wrist Pins are added to finish the Stage 2.5 short block.

Stage 2.5 Closed Deck Includes:

• Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
• Pistons - IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Ring Set, .180" Chromoly Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
• Connecting Rods - IAG-Spec Tuff H-Beam / ARP2000 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.

Power:

• The IAG Stage 2.5 Short Block has a power output rating of 675BHP.

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 Recommendations:

• IAG Recommends JE Pro Seal .039 inch head gaskets (Sold Separately)

Additional Options Available:

• Oil Pump - Subaru JDM 12mm High Volume Oil Pump or 11mm Subaru Oil Pump (Sold Separately)
• Head Gaskets - JE Pro Seal .039 inch Head Gaskets (Sold Separately)
• Hardware/Seals - OEM cover and seal kit (Sold Separately)

Not planning on reusing your original short block service plugs and covers? IAG offers a simple comprehensive cover and seal kit that includes:

• (1) Rear main seal
• (3) OEM wrist pin plugs
• (3) OEM wrist pin plug washers
• (1) OEM separator cover
• (6) OEM separator cover bolts
• (1) OEM wrist pin service cover
• (1) OEM wrist pin service cover O-ring
• (2) OEM wrist pin service cover screws.

If you are reusing your original wrist pin service plugs and covers always replace the following components before installing a short block to avoid potential leaks:

• (3) OEM wrist pin plug washers
• (1) wrist pin service cover O-ring

Never reuse a rear main seal on a new short block.

Note: All IAG Short Blocks are balanced and blueprinted.

Please review the PDF document below regarding installation, break-in procedures and warranty information.