IAG’s 950 EJ25 2.35L Destroked Closed Deck Short Block is designed to support up to 950 BHP while maintaining the reliability needed for street-driven vehicles. Hand-assembled by IAG’s experienced engine builders, this short block is based on the proven IAG 950 platform and features a Subaru 2.0L FHI crankshaft, custom IAG Spec +2mm H-beam forged connecting rods with ARP 625+ rod bolts, and JE 99.75mm FSR 2618 forged pistons with electroless nickel plating for improved detonation resistance and heat control. The result is a durable, high-revving engine foundation built for both performance and longevity.

The destroked design reduces piston speed, improves the rod-to-stroke ratio, and increases piston dwell time at top dead center. This enhances combustion efficiency, reduces stress at high RPM, and allows the engine to safely rev up to 8,500 RPM, making it well-suited for road racing, rally, and drag racing applications.

Each short block starts with brand-new Subaru 2.5L case halves that are CNC-machined in-house to accept IAG’s proprietary closed deck inserts. The cylinders are bored and honed to 99.75mm with torque plates to ensure precise clearances, quiet operation, and controlled oil consumption. The case is also machined to accept IAG’s Fire-Lock™ head gasket system and 14mm head studs. All assemblies are balanced and blueprinted and include ACL rod and main bearings.

IAG’s Fire-Lock™ head gasket system separates combustion sealing from oil and coolant sealing, providing a proven solution for extreme cylinder pressures. Combined with the reinforced closed deck design, this system prevents cylinder wall flex and head gasket failure while retaining proper coolant flow for street use.

Included:

• Case Halves - Brand new Subaru OEM case halves
• 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 - JE 99.75mm FSR 2618 Custom Pistons and .240" H13 Tool Steel Wrist Pins with JE Pro Seal Ring Set
• Connecting Rods - Custom IAG spec +2mm H-Beam Forged Connecting Rods and ARP 625+ Rod Bolts.
• Rod / Main Bearings - ACL Race Bearings
• Crankshaft - 2.0L FHI Crankshaft
• Case / Main Bolts - Standard FHI Subaru case bolts.

Additional Information:

Head Gasket Required:

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

Compression Ratio: All calculated with Fire-Lock gaskets

• 9.2:1 on D Cylinder Heads (EJ255)
• 8.8:1 on B, V, and W EJ257 Heads