IAG 600 FA20 DIT Subaru Short Block for 2015-21 WRX – 600 BHP

Part Details:

The IAG 600 FA20 DIT Short Block is a performance-built engine foundation designed specifically for the 2015–2021 Subaru WRX equipped with the FA20 DIT engine. Engineered for reliable power gains up to 600 BHP, this short block provides increased strength and durability for tuned street cars and moderate turbo upgrades.

Built using brand-new Subaru FA20 case halves and upgraded forged internals, the IAG 600 is intended for enthusiasts who want improved reliability under boost without stepping into extreme race-focused engine builds.

Engine Construction & Machining

Each IAG 600 FA20 short block starts with brand-new OEM Subaru FA20 case halves that are professionally machined for improved oiling and bored and honed to 86.25mm. These machining upgrades help improve lubrication under higher load and RPM conditions, reducing stress on internal components.

The result is a stronger and more reliable foundation compared to the factory FA20 short block, especially when paired with upgraded turbochargers and tuning.

Engine Internals & Components

The rotating assembly features IAG-spec forged pistons measuring 86.25mm, designed to handle increased cylinder pressure while maintaining durability for daily-driven performance vehicles. These pistons are paired with carbon steel wrist pins and a matched ring set for reliable sealing under boost.

IAG-spec H-beam connecting rods secured with ARP2000 rod bolts provide improved strength over factory components. ACL or King XPG rod and main bearings are used throughout to support consistent oil clearances and durability at elevated power levels. A new OEM Subaru FA20 DIT crankshaft completes the rotating assembly.

Reliability & Performance Benefits

As power levels increase, factory FA20 short blocks can become a reliability concern. The IAG 600 FA20 DIT addresses these limitations by reinforcing the rotating assembly and improving internal clearances, helping reduce the risk of engine failure in tuned and modified applications.

This short block is well-suited for daily-driven WRXs, weekend performance builds, and vehicles running moderate turbo upgrades where long-term reliability is a priority.

Vehicle Fitment Overview

This short block is 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 short block, not a stock replacement. Vehicle configuration, supporting modifications, and tuning goals should always be verified prior to purchase.

What’s Included

• Brand-new OEM Subaru FA20 case halves
• Case machining for improved oiling
• Bored and honed to 86.25mm
• IAG-spec 86.25mm forged pistons with ring set
• 0.150″ x 2.250″ 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 crankshaft
• OEM Subaru case and main bolts
• OEM oil plug pre-installed at oil pan location

Compression Ratio

• 10.5:1 compression ratio with standard head gasket thickness

Installation & Build Notes

• Professional installation is strongly recommended
• ECU tuning is required
• Supporting modifications (fueling, turbocharger, cooling) are recommended for higher power levels
• Final power capability depends on the complete build and tuning strategy

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