IAG Stage 1 Plus Short Block 2.5L Subaru WRX / STI / Legacy GT / Forester XT 2002-2017

IAG Performance
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The IAG Stage 1 Plus short block starts with new Subaru 2.5L EJ25 engine case halves that are bored and honed to 99.75mm on our in house Sunnen SV-10. IAG‘s in house honing process is able to set piston to wall clearances tighter for a quieter running engine. The short block is measured and assembled using a new 2012+ Subaru 2.5L heat-treated STI crankshaft that is matched to ACL Race main bearings. Early style OEM STI rods are utilized along with ACL rod bearings. The case halves are sealed with new OEM case bolts and sealant. Finally Manley 99.75mm Platinum Series Forged Pistons are spec'd and installed finishing off the short block. 

The IAG Stage 1 Plus Short Block has a power output rating of 475BHP.

*All IAG Short Blocks are balanced and blueprinted. 

Compression Ratio: 8.5:1 on D Cylinder Heads (EJ255) 
Compression Ratio: 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.

Not planning on reusing your original short block service plugs and covers? IAG offers a simple comprehensive cover and seal kit that includes the (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 and (2) OEM wrist pin service cover screws. *If you are reusing your original wrist pin service plugs and covers always replace the (3) OEM wrist pin plug washers and (1) wrist pin service cover O-ring before installing a short block to avoid potential leaks.


  • Manley 99.75mm Platinum Series Pistons, Ringset, Tool Steel Pins and Clips (w/ Coated Skirts and Offset Wrist Pin)
  • New FHI Subaru Case Halves at 99.75mm 
  • New FHI Subaru Early STI (Stronger Style) Connecting Rods
  • New FHI Subaru Heat Treated 2012+ STI Crankshaft
  • ACL Rod Bearings
  • ACL Main Bearings
  • New FHI Main Case Bolts
  • IAG Spec Blueprint Sheet
  • Power Output Rating: 475BHP

**All engines come in a pelican case which must be returned, free of charge, within 7 days of delivery. There will be a $250 fee if case not returned**


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