IAG Performance 1000 Series FA20 Closed Deck Short Block 2015-2021 WRX | 1000 BHP Capacity | High-Strength Engine Assembly

Overview

The IAG Performance 1000 Series FA20 Closed Deck Short Block is a purpose-built engine foundation designed for Subaru WRX owners seeking extreme power and uncompromising durability. Engineered to support up to 1000 brake horsepower, this short block is ideal for enthusiasts pushing the limits of forced induction and high-boost applications. Whether you’re building a street car, drag racer, or track weapon, this assembly delivers the strength and reliability needed to handle serious cylinder pressures without failure.

At the core of this short block is a precision-machined closed deck conversion that reinforces the factory FA20 engine case halves. IAG’s engineering approach combines advanced CNC machining with cryogenically cooled inserts to create a mechanically locked closed deck structure that resists cylinder wall movement and cracking. The design maintains proper coolant flow through integrated passages, ensuring optimal thermal management despite the added strength. This attention to detail reflects IAG’s commitment to race-proven durability and real-world reliability.

Subaru owners benefit from a fully balanced and blueprinted assembly featuring forged JE pistons with nickel plating, H-beam connecting rods with ARP 625+ bolts, and premium ACL or King rod and main bearings. The inclusion of the proprietary Fire-Lock head gasket system (sold separately) and compatibility with 14mm head studs ensures a secure combustion seal under extreme boost. This short block is a solid foundation for high-output FA20 builds, delivering peace of mind alongside serious power potential.

Features & Specifications

This IAG Performance 1000 Series FA20 Closed Deck Short Block is engineered specifically for 2015-2021 Subaru WRX models and features a closed deck conversion with forged internals. Constructed from brand-new OEM Subaru FA20F case halves and high-strength forged components, it delivers a robust platform capable of supporting up to 1000 BHP for Subaru enthusiasts pursuing high-boost performance.

• Brand: IAG Performance
• Product: 1000 Series FA20 Closed Deck Short Block
• Part Number: IAG-ENG-S1020
• Fitment: 2015-2021 Subaru WRX
• Material: Forged 2618 Alloy Pistons, H-Beam Forged Connecting Rods, OEM Subaru FA20F Case Halves
• Finish: Electroless Nickel Plated Pistons, Precision Machined Case
• Construction: CNC Machined Closed Deck Conversion, Hand-Assembled
• Origin: Assembled in USA
• Power Gains: Supports up to 1000 BHP
• Compression Ratio: 10:1
• Tuning Required: Yes, for high boost and power levels

Key Benefits

• Performance: Supports extreme power levels up to 1000 BHP with forged internals designed for high boost applications.
• Durability: Closed deck conversion significantly strengthens the engine block to resist cylinder wall movement and cracking under stress.
• Reliability: Hand-assembled with premium ACL or King bearings and balanced components for consistent, long-lasting operation.
• Cooling Efficiency: Integrated coolant passages in closed deck inserts maintain optimal thermal management despite increased block rigidity.
• Fitment: Direct fit for 2015-2021 Subaru WRX FA20 engines, maintaining OEM compatibility with upgraded performance.
• Sealing Technology: Designed to accept the IAG Fire-Lock head gasket system and 14mm head studs for superior combustion sealing under extreme conditions.

What's Included

• 1× IAG Performance 1000 Series FA20 Closed Deck Short Block
• Brand-new OEM Subaru FA20F case halves converted to closed deck
• IAG-Spec JE Forged 2618 Alloy Pistons with Electroless Nickel Plating
• IAG-Spec H-Beam Forged Connecting Rods with ARP 625+ Rod Bolts
• New Subaru FA20 Crankshaft
• ACL or King Race Rod and Main Bearings
• Case and Main Bolts with Factory Sealant
• Precision CNC Machined Closed Deck Inserts and Deck Plates
• Fire-Lock Receiver Groove Machining (Fire-Lock Gaskets and 14mm Head Studs sold separately)
• Installation instructions included

Installation & Compatibility

Installation of the IAG 1000 FA20 Closed Deck Short Block is a complex process best suited for professional engine builders or experienced enthusiasts with advanced mechanical skills. The assembly requires precise torque application and compatibility with the IAG Fire-Lock head gasket system and 14mm head studs, which are sold separately. Proper tuning is essential to safely realize the power potential and maintain engine longevity. This short block is a direct fit for 2015-2021 Subaru WRX models equipped with the FA20 engine but verify your specific year and trim for compatibility. Additional machining or overboring may be necessary if the block or cylinder head was previously modified.

• Professional Installation: Recommended
• Modifications Required: Requires Fire-Lock head gaskets and 14mm head studs (sold separately); possible overbore if previously honed
• Verify Compatibility: Confirm fitment for your specific 2015-2021 WRX model and engine condition

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