IAG 800 FA20 DIT Closed Deck Long Block Engine w/ IAG 800 Heads for 2015-21 Subaru WRX

Part Details:

The IAG 800 FA20 DIT Closed Deck Long Block Engine with IAG 800 Heads is a fully assembled, high-strength engine package built for 2015–2021 Subaru WRX models equipped with the FA20 DIT engine. Designed for builds targeting up to 800 BHP, this long block combines a reinforced closed deck short block with CNC pocket-ported cylinder heads to deliver improved cylinder stability, increased airflow, and reliable performance under high boost.

This package is well suited for big-turbo street builds, aggressive E85 setups, and demanding track applications where the factory FA20 architecture becomes a reliability concern.

Vehicle Fitment Overview

Designed for Subaru WRX models equipped with the FA20 DIT engine. Full year-by-year compatibility is listed in the Vehicle Fitment tab above.

This is a 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 the closed deck short block, fully assembled CNC-ported cylinder heads, and the gaskets and hardware listed below (including OEM timing components and OEM oil pump/timing cover as listed).

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 800 BHP
• Final power capability depends on turbo system, fueling, cooling, and tuning quality
• Professional installation is strongly recommended
• ECU tuning is required

IAG 800 FA20 DIT Closed Deck Short Block

• Brand-new OEM Subaru FA20 case halves, bored and honed to 86.1mm
• Case machining modified for improved oiling
• Closed deck conversion with deck surface O-ringing
• Machined for 1/2″ head studs (head studs sold separately for the short block)
• IAG-spec 86.1mm forged pistons with ring set
• 0.230″ x 2.250″ 9310 nickel carbon steel wrist pins
• IAG-spec H-beam connecting rods with ARP2000 rod bolts
• ACL or King XPG rod bearings
• ACL or King XPG main bearings
• New OEM Subaru FA20 DIT WRX crankshaft
• OEM Subaru case and main bolts
• OEM oil plug pre-installed at the oil pan location

Compression Ratio

• 10.5:1 compression ratio with standard head gasket thickness

IAG 800 CNC Pocket-Ported FA20 DIT Cylinder Heads

• Two brand-new Subaru OEM AW20 FA20 WRX DIT cylinder head castings
• GSC 35mm (+1mm) intake valves
• GSC 30mm (+1mm) exhaust valves
• Kelford dual cylindrical valve springs and retainers
• GSC manganese-bronze valve guides
• GSC valve stem seals
• IAG Performance CNC pocket porting
• Multi-angle valve job
• Drilled for compatibility with 1/2″ or 14mm head studs
• Threaded coolant plug upgrade
• Resurfacing and ultrasonic cleaning
• Kelford “A” 272 camshafts
• OEM cam towers and hardware
• OEM rocker pivots
• OEM lifters
• OEM valve lash caps
• Valve lash service completed

Gaskets, Hardware & Accessories

• ARP 2000 1/2″ head stud set
• OEM head gaskets
• OEM valve cover gaskets
• OEM valve covers
• OEM timing components
• OEM oil pump and timing cover
• Rear main seal and separator kit
• Crankshaft woodruff key

Installation & Build Notes

• Designed for big-turbo, E85, and high-boost FA20 DIT builds
• Supporting modifications (fuel system, turbo system, cooling, oiling) should match power goals
• 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