IAG 1150 Closed Deck Long Block Engine w/ IAG 1150 Heads for 02-14 WRX, 04-21 STI, 04-13 FXT, 05-09 LGT

Part Details:

The IAG 1150 Closed Deck Long Block Engine with IAG 1150 Cylinder Heads is an elite, competition-level engine package built for Subaru EJ25 platforms targeting extreme horsepower. Designed to support builds up to 1,150 BHP, this long block combines IAG’s fully CNC-machined closed deck 1150 short block with fully CNC-ported IAG 1150 cylinder heads and a race-grade valvetrain for maximum durability, airflow, and cylinder stability.

This engine package is intended for high-boost, big-turbo, E85, and drag racing applications where absolute reliability and consistent performance at extreme power levels are critical.

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

What This Long Block Includes

This is a complete long block assembly that includes a fully machined closed deck short block, 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 1,150 BHP
• Final power capability depends on turbo system, fueling, cooling, and tuning quality
• Professional installation is strongly recommended
• ECU tuning is required

IAG 1150 Closed Deck EJ25 Short Block

• Brand-new Subaru OEM EJ25 case halves converted to closed deck
• Bored and honed to 99.75mm
• Machined for 9.5mm pinned mains and line-honed
• IAG Fire-Lock™ receiver groove machining (Fire-Lock™ head gaskets required)
• Machined for 14mm head studs
• IAG-spec JE FSR 99.75mm 2618 forged pistons with electroless nickel-plated crowns and ring lands
• 0.250″ / 0.927″ H13 wrist pins with skirt coating and offset wrist pins
• IAG-spec +2mm Tri-Beam connecting rods with ARP 625+ rod bolts
• ACL or King race rod and main bearings
• IAG-spec billet crankshaft
• ARP main bolts

IAG 1150 Fully CNC Ported Cylinder Heads

• Brand-new Subaru OEM WRX STI cylinder head castings
• Fully CNC-ported intake and exhaust runners
• Ferrea 37mm (+1mm) Comp Plus intake valves
• Ferrea 33mm (+1mm) Comp Plus exhaust valves
• Ferrea dual valve springs with titanium retainers
• Ferrea valve keepers
• GSC manganese bronze valve guides
• GSC valve stem seals
• Kelford DLC-coated lifter buckets
• GSC Stage 2 or Stage 3 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 extreme horsepower, drag racing, and high-boost 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

Performance Airflow Upgrades

• Corsa Veloce Stradale Rear-Facing Intake Manifold– increases airflow and supports high-horsepower EJ engine builds

Learn more about IAG Performance engine and reliability solutions