IAG 950 Closed Deck Long Block Engine w/ IAG 950 Heads for 02-14 WRX, 04-21 STI, 04-13 FXT, 05-09 LGT

Part Details:

The IAG 950 Closed Deck Long Block Engine with IAG 950 Cylinder Heads is a competition-ready, fully assembled engine package built for Subaru EJ platforms targeting extreme horsepower. Rated for builds up to 950 BHP, this long block pairs a closed-deck IAG 950 short block with CNC-ported IAG 950 cylinder heads and a race-proven valvetrain to deliver exceptional cylinder stability, airflow, and durability under high boost.

Designed for big-turbo street builds, strip use, and track-focused applications, this engine package is a strong choice when you need a complete long block solution engineered to handle sustained boost and demanding conditions.

Vehicle Fitment Overview

Designed for Subaru EJ-series platforms including WRX, STI, Forester XT, and Legacy GT models. Full year-by-year compatibility is listed in the Vehicle Fitment tab above.

This is a high-performance long block, not a stock replacement. Vehicle configuration, emissions requirements, and overall build goals should always be verified prior to purchase.

What This Long Block Includes

This is a complete long block assembly that includes a closed deck short block (EJ25 or EJ20 option), fully assembled CNC-ported cylinder heads, and the gaskets and hardware listed below.

Important Notes: What’s Not Included

• Intake manifold
• Turbocharger and turbo system components
• Fuel injectors and fuel system components
• Accessory components (alternator, A/C compressor, etc.)
• ECU calibration (tuning)

Power & Build Expectations

• Rated for builds targeting up to 950 BHP
• Final power capability depends on turbo system, fueling, cooling, and tuning quality
• Professional installation is strongly recommended
• ECU tuning is required

IAG 950 Closed Deck Short Block Options

EJ25 2.5L Closed Deck Short Block

• Brand-new Subaru OEM EJ25 case halves converted to closed deck
• Bored and honed to 99.75mm
• IAG Fire-Lock™ receiver groove machining (Fire-Lock™ head gaskets required)
• Machined for 14mm head studs (head studs sold separately for the short block)
• IAG-spec JE FSR 99.75mm 2618 forged pistons with electroless nickel-plated crowns and ring lands
• 0.250″ / 0.906″ H13 wrist pins with skirt coating and offset wrist pins
• IAG-spec Tuff H-beam +2mm connecting rods with ARP 625+ rod bolts
• ACL or King race rod and main bearings
• New Subaru nitride-treated STI crankshaft (2017+)
• OEM Subaru case and main bolts

EJ20 2.0L Closed Deck Short Block

• Brand-new Subaru OEM EJ20 case halves converted to closed deck
• Bored and honed to 92.5mm
• IAG Fire-Lock™ receiver groove machining (Fire-Lock™ head gaskets required)
• Machined for 14mm head studs (head studs sold separately for the short block)
• IAG-spec JE FSR 92.5mm 2618 forged pistons with electroless nickel-plated crowns and ring lands
• 0.250″ / 0.906″ H13 wrist pins with skirt coating and offset wrist pins
• IAG-spec Tuff H-beam +2mm connecting rods with ARP 625+ rod bolts
• ACL or King race rod and main bearings
• New Subaru EJ20 crankshaft
• OEM Subaru case and main bolts

IAG 950 CNC Ported Cylinder Heads

• Brand-new Subaru OEM WRX STI cylinder head castings
• Fully CNC-ported intake and exhaust runners
• GSC 37mm (+1mm) intake valves
• GSC 33mm (+1mm) SuperAlloy exhaust valves
• IAG-spec beehive valve springs and retainers
• GSC manganese valve guides
• GSC valve stem seals
• Kelford DLC-coated lifter buckets
• GSC Stage 2 billet camshafts
• Multi-angle valve job
• Machined cam lobe clearance
• Drilled for 14mm head studs
• Resurfacing, ultrasonic cleaning, and final lash set

Gaskets, Hardware & Accessories

• IAG / ARP 14mm head stud set
• IAG Fire-Lock™ head gaskets
• OEM valve cover gaskets
• OEM cam seals
• OEM valve covers
• Wrist pin seal, rear main seal, and separator kit
• Crankshaft woodruff key

Installation & Build Notes

• Designed for big-turbo, high-boost, and competition-oriented EJ builds
• Supporting modifications (fuel system, turbo system, cooling, oiling) must match power goals
• Fire-Lock™ head gasket requirements must be followed for proper sealing
• Break-in procedures and oil selection should follow engine builder recommendations
• Final results depend on the complete setup and professional tuning

Recommended Supporting Upgrades

• Air / Oil Separator (AOS) – helps reduce oil vapor ingestion and protect the intake system
• Oil pickup and baffle upgrades – improves oil control and reduces bearing failure risk
• Long block installation kits – simplifies installation with required gaskets and hardware
• Engine installation fluid kits – includes break-in oil and coolant for first startup

Learn more about IAG Performance engine and reliability solutions