IAG 1150 2.35L Destroked 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 2.35L Destroked Long Block Engine with IAG 1150 Cylinder Heads is a top-tier, motorsport-grade EJ engine package designed for extreme horsepower with high-RPM reliability. Rated for builds targeting up to 1,150 BHP, this long block combines a 2.35L destroked closed-deck IAG 1150 short block with fully CNC-ported IAG 1150 cylinder heads and a race-grade valvetrain for maximum durability, airflow, and stability under severe boost and sustained engine speed.

A destroked configuration is commonly chosen for competitive use because it improves rod ratio, enhances reliability at elevated RPM, and delivers sharper throttle response—making it an ideal foundation for drag racing, track-focused builds, and big-turbo Subaru setups that live in the upper RPM range.

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 the 2.35L destroked 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 2.35L Destroked Closed Deck Short Block

• Brand-new Subaru OEM case halves
• 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
• JE 99.75mm FSR 2618 custom pistons
• 0.240″ / 0.906″ H13 wrist pins
• JE ProSeal ring set
• Custom IAG-spec +2mm Tri-Beam forged connecting rods with ARP 625+ rod bolts
• ACL race rod and main bearings
• IAG-spec billet 75mm crankshaft (destroked configuration)
• ARP case and main bolts

Compression Ratio

All compression ratios are calculated using IAG Fire-Lock™ head gaskets:

• 9.2:1 – EJ255 (D heads)
• 8.8:1 – EJ257 (B, V, W heads)

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-RPM 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