IAG Performance 1150 Series High Compression Closed Deck EJ25 Short Block 2006-2014 WRX / 2004-2021 STI / 2004-2013 Forester XT / 2005-2009 Legacy GT

IAG Performance 1150 Series High Compression Closed Deck EJ25 Short Block 2006-2014 WRX / 2004-2021 STI / 2004-2013 Forester XT / 2005-2009 Legacy GT

This high compression version of the IAG 1150 short block is intended for E85, race gas and other high-octane fuels. It fits the 2006-2014 WRX, 2004-2021 STI, 2004-2013 Forester XT and 2005-2009 Legacy GT. It shares the strengthened 1150 platform but uses flat-top pistons to raise compression for drag racing, while staying street-usable.

Build details

• Case halves: Brand new OEM Subaru, converted to Stage 4 closed deck, deck plate bored and honed to 99.75mm
• Pinned mains: Machined for 9.5mm pins and line honed; ARP main bolts
• Head sealing: Fire-Lock receiver groove machining; machined for 14mm head studs
• Crankshaft: IAG-Spec billet
• Connecting rods: IAG-Spec +2mm Tri-Beam with ARP 625+ rod bolts
• Pistons: IAG-Spec JE FSR 99.75mm 2618 forged, flat-top, electroless nickel plated tops and ring area, .250" wall / .927" diameter H13 wrist pins, clips, gas ports, Perfect Skirt coating and offset wrist pins
• Bearings: ACL or King race bearings
• Compression ratio: 9.9:1 on D heads (EJ255); 9.5:1 on B, V and W EJ257 heads
• Components: 100% new parts

Before you order

IAG Fire-Lock .051" head gaskets with the IAG-Spec Alloy Ring Set (PN IAG-ENG-1741) are required. The higher compression is meant for high-octane fuel such as E85 or race gas, so plan your fuel and tune around it. Send us your VIN or engine code and we will confirm fitment before you order.

See also: Subaru oil pickup tube problems · FA20 vs EJ25 · head studs vs head bolts · EJ257 problems · is it worth replacing an engine? · Subaru head gasket problems and ringland failure · signs of a blown head gasket · Subaru WRX and STI parts · EJ255 vs EJ257 · subaru ej25 / ej257 · IAG Performance Subaru blocks and all engines by engine code.

Shipping and returns

Shipping is a flat $80.00 per order to US addresses, and returns are free within 15 days of delivery. Questions before you order? Ask a parts specialist.