Boundary FA20F-14MM-OPG Billet Oil Pump Gear for 2015-2021 Subaru WRX FA20F

Vehicle Fitment

• 2015-2021 Subaru WRX (FA20F / FA20DIT 2.0L Turbocharged H4, Direct Injection, All Transmissions)

Fitment Notes

• Fits the FA20F (also known as FA20DIT) turbocharged, direct-injection engine ONLY - uses a 14mm gear set unique to this engine's higher-demand oil system
• Does NOT fit the naturally aspirated FA20D engine found in the Subaru BRZ, Toyota 86, or Scion FR-S - those applications require the FA20D-12MM-OPG (12mm gearset)
• Does NOT fit the 2014 Subaru Forester XT (FA20E variant) without confirmation - the FA20E shares architecture with the FA20F but has a separate engine designation; verify with Boundary before ordering
• Does NOT fit the 2022+ Subaru WRX, which uses the new FA24 2.4L turbocharged engine - an entirely different engine family
• Does NOT fit the Subaru WRX STI, which retains the EJ257 engine through the 2021 model year
• Available in two variants at checkout: No Treatment (standard billet) or MartenWear Treatment (extreme-duty surface hardening)
• Inner and outer gears machined and shipped as a matched set - sold as a complete gearset (1 set per unit)
• Made 100% in the USA with US-sourced materials

Features

• Chromoly billet steel construction - approximately 18x stronger than OEM sintered/powdered metal gears (Boundary billet approaches 110,000 PSI yield strength vs. ~6,000 PSI for OEM powdered metal)
• Hot quenched from extreme heat and tempered to an indestructible core for maximum toughness throughout the gear body
• ColdFlow surface hardening process applied after machining for a mirror finish with exceptional wear resistance on the standard (No Treatment) variant
• MartenWear Treatment (optional upgrade): a second-stage in-house heat treatment hardening the exterior surface to Vickers 620-720 (Rockwell C 55-60), proven wear-free at 13,000+ RPM and highly resistant to debris ingestion
• Surface ground gears for the ultimate in dimensional accuracy, fitment, and oil flow efficiency
• Inner and outer gears machined in matched sets for zero tolerance stacking and optimal gerotor meshing
• Race-inspired gerotor design optimized for maximum oil flow and structural strength under sustained boost and high-RPM operation
• Mirror finish reduces friction and heat generation critical in a turbocharged application where oil system demands are significantly higher than naturally aspirated
• Every set hand-inspected, machine-inspected, and hardness-tested, shipped with a Blueprinting Report confirming dimensional and hardness specifications
• Made 100% in the USA at Boundary's Texas facility
• Backed by Boundary's Limited Lifetime Warranty

Specifications

• Part Number: FA20F-14MM-OPG
• Part Type: Billet Oil Pump Gearset (Inner + Outer Gerotor)
• Engine Application: Subaru FA20F / FA20DIT 2.0L Turbocharged H4 (WRX 2015-2021)
• Gear Size: 14mm
• Material: Chromoly Billet Steel (US-Sourced)
• Standard Finish: ColdFlow Mirror Surface Hardened
• MartenWear Surface Hardness (optional): Vickers 620-720 / Rockwell C 55-60
• Verified Maximum RPM (MartenWear): 13,000+ RPM (wear-free)
• Sold: As a matched inner and outer gear set (1 set per unit)
• Includes: Blueprinting Report confirming dimensional and hardness specifications
• Country of Origin: USA

Included Components

• 1x Inner Oil Pump Gear (FA20F 14mm, billet chromoly)
• 1x Outer Oil Pump Gear (FA20F 14mm, billet chromoly, matched to inner gear)
• 1x Blueprinting Report (dimensional and hardness inspection documentation)

Product Description

The Boundary FA20F-14MM-OPG is a billet chromoly oil pump gearset engineered specifically for the FA20F (FA20DIT) turbocharged engine found in the 2015-2021 Subaru WRX. The FA20F's factory oil pump uses sintered (powdered metal) gears - a cost-efficient manufacturing method that produces a structurally weak gear material with a yield strength of approximately 6,000 PSI. In a turbocharged application like the WRX, where the oil system is under significantly higher thermal and mechanical stress than a naturally aspirated engine, these OEM gears represent a genuine reliability risk - particularly for modified builds running elevated boost, high-RPM track use, or aggressive driving schedules. Boundary's 14mm gearset is machined from solid US-sourced chromoly billet steel, hot quenched and core-tempered to a yield strength approaching 110,000 PSI - approximately 18 times stronger than the OEM sintered material.

The 14mm gear size is specific to the FA20F/FA20DIT's oil pump housing and reflects the turbocharged engine's greater oil volume and pressure demands compared to the naturally aspirated FA20D (which uses a 12mm gearset). Every FA20F-14MM-OPG set is produced entirely in-house at Boundary's Texas manufacturing facility using US-sourced chromoly billets. Inner and outer gerotor gears are machined as a matched set, eliminating tolerance stacking between gears and ensuring optimal oil flow geometry and meshing accuracy that mismatched or mass-produced gears cannot achieve. After machining, Boundary applies their ColdFlow surface hardening process, bringing gear surfaces to a mirror finish for reduced friction and improved wear characteristics. The optional MartenWear upgrade adds a second stage of proprietary in-house surface heat treatment, hardening the exterior to Vickers 620-720 (Rockwell C 55-60) - validated by Boundary to be wear-free at 13,000+ RPM and exceptionally resistant to contaminated-oil debris that can rapidly destroy sintered OEM gears.

Every completed set is hand-inspected, machine-inspected, and hardness-tested before shipping, and is accompanied by a Blueprinting Report confirming all key dimensional and hardness specifications. This part number is exclusive to the FA20F/FA20DIT turbocharged engine in the 2015-2021 WRX. It is not compatible with the naturally aspirated FA20D (BRZ/86/FR-S), the 2022+ WRX (FA24 engine), or the WRX STI (EJ257 engine). Made 100% in the USA, and backed by Boundary's Limited Lifetime Warranty.