IAG Performance 950 EJ25 Closed Deck Short Block

Subaru WRX/STI/LGT/FXT

The IAG Performance 950 EJ25 Closed Deck Short Block represents the pinnacle of Subaru engine building, engineered for extreme power applications where reliability under stress is non-negotiable. Built with a closed deck design for maximum cylinder strength, this short block is ready to handle serious boost and track abuse.

Usually Ships In 2-3 Weeks

What's Included

IAG 950 Closed Deck EJ25 Short Block 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

Compression Ratio

• 9.1:1 on D Cylinder Heads (EJ255)
• 8.8:1 on B, V and W EJ257 Heads with IAG Fire-Lock™ head gaskets

Head Gasket Required

• *IAG Fire-Lock™ .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1741

Key Features

• Closed Deck Block Design: Superior cylinder wall support for extreme boost applications
• Power Capacity: Designed to support 950+ BHP (710+ kW)
• IAG Fire-Lock Technology: Proprietary receiver groove machining prevents head gasket failure
• Precision Machined: 99.75mm bore with CNC-machined closed deck conversion
• Forged Internals: JE FSR forged pistons with electroless nickel plating
• Performance Bearings: ACL or King Race Series bearings
• Upgraded Crankshaft: Nitride treated 2017+ STI crankshaft
• Quality Assurance: Each engine is individually tested and inspected

Fitment

• Subaru WRX (2002-2014)
• Subaru STI (2004-2021)
• Subaru Legacy GT (2005-2012)
• Subaru Forester XT (2004-2013)

Why Choose IAG Performance?

IAG Performance has built a reputation as one of the most trusted names in Subaru performance engineering. With decades of experience in motorsport and high-performance street applications, their closed deck short blocks are designed for enthusiasts who demand the absolute best foundation for high-horsepower builds. The proprietary Fire-Lock technology provides an additional layer of protection against head gasket failure, a common issue in high-boost applications.

Installation Notes

Professional installation is strongly recommended. This short block requires additional components including cylinder heads, IAG Fire-Lock head gaskets (PN# IAG-ENG-1741), 14mm head studs (sold separately), timing components, oil pump, water pump, and all associated gaskets and seals. Custom tuning is mandatory for proper operation and to achieve rated power levels.

Note: This is a short block only. Cylinder heads, Fire-Lock head gaskets, head studs, timing components, and accessories are not included. Lead time is typically 4-6 weeks from order date.