BC0620 – Brian Crower Stage 2+ Performance Camshafts for Subaru EJ257/EJ255

For the builder seeking to extract the definitive performance envelope from a fully built Subaru EJ25 platform, the selection of valvetrain components is not a matter of preference—it is a critical engineering decision. The BC0620 Brian Crower Stage 2+ Camshafts represent a calculated evolution beyond aggressive street profiles, engineered specifically for forced-induction applications where mid-range torque and top-end horsepower are non-negotiable. These are not generic regrinds; they are billet cores, precision-machined to BC’s proprietary Stage 2+ specifications, designed to work in harmony with upgraded valvetrains, larger turbochargers, and fortified bottom ends. Targeting the discerning enthusiast and professional tuner alike, this camshaft set transforms the breathing characteristics of the EJ257/EJ255 engine, shifting the volumetric efficiency curve decisively toward the upper RPM band while maintaining controllable street manners. When paired with appropriate supporting modifications, the BC0620 cams are the key to unlocking a broader, flatter torque curve and significantly raising the engine’s horsepower potential, pushing built motors consistently beyond the 500-600+ WHP threshold.

Engineering Philosophy & Design Specifications

The BC0620 profile is predicated on a fundamental principle: optimizing air exchange efficiency in a turbocharged, four-valve-per-cylinder engine. Brian Crower’s engineers start with a premium-grade, virgin 8620 steel billet, CNC-machined to exacting tolerances for lobe concentricity and base circle consistency. The Stage 2+ designation indicates a profile with increased duration and lift over stock and Stage 1/2 grinds, engineered to extend the engine’s effective power band. Increased duration holds the valves open longer, improving cylinder filling and scavenging, especially at higher engine speeds where turbochargers are operating most efficiently. Simultaneously, the increased lift provides a larger curtain area for airflow at peak valve opening, reducing restriction and supporting greater mass airflow. Crucially, these cams retain the factory AVCS (Active Valve Control System) provisions on the intake camshafts, allowing modern engine management systems to fine-tune low-end response and overlap, a critical feature for maintaining driveability and spool characteristics. The lobes are precision-ground and micro-polished to minimize friction and wear on follower interfaces, ensuring longevity in high-stress environments.

Valvetrain Synergy & Compatibility Requirements

It is imperative to understand that the BC0620 camshafts operate as part of a system. Their increased lift and aggressive ramp rates mandate the use of upgraded valve springs and titanium retainers—such as Brian Crower’s matching BC0607 spring kit—to prevent valve float and ensure precise valve closure at elevated RPMs. Utilizing stock springs with these cams risks catastrophic valvetrain failure. Furthermore, these cams are designed for engines with forged internal components (pistons, rods, crank) and a turbocharger upgrade capable of flowing significantly more air than the stock unit. They are ideally suited for applications where the cylinder heads have been professionally ported or feature larger valves, as the camshaft’s improved flow potential can then be fully realized by the entire intake and exhaust tract. Installation requires precise timing and, typically, adjustable cam gears for fine-tuning the power band, making professional installation and a comprehensive dyno tuning session absolutely essential.

Performance Benefits & Application Profile

The installation of BC0620 Stage 2+ Camshafts is a transformative upgrade that alters the fundamental character of a built EJ25. The benefits are measurable and significant:

• Extended High-RPM Power Band: Shifts the engine’s volumetric efficiency peak higher, allowing it to continue making power well beyond the stock redline, essential for large-frame turbo applications.
• Increased Peak Horsepower & Torque: By improving cylinder scavenging and filling, these cams directly support greater mass airflow, translating to substantial gains in both peak and area-under-the-curve metrics.
• Enhanced Turbocharger Response & Efficiency: Improved exhaust scavenging helps spool the turbocharger more effectively and can reduce exhaust backpressure, allowing the turbo to operate more efficiently across the rev range.
• AVCS Compatibility for Tunability: Retention of the factory AVCS system allows tuners to optimize low-speed torque and transient response, mitigating traditional trade-offs associated with aggressive cam profiles.
• Billet Core Strength & Durability: Manufactured from 8620 steel billet, these cams offer superior structural integrity and wear resistance compared to reground stock cores, ensuring reliability under high spring pressures and RPM.

These cams are the definitive choice for serious street/strip builds, time-attack vehicles, and dedicated track cars where maximum power output from a built 2.5L Subaru engine is the primary objective. For an in-depth technical analysis of optimizing AVCS tuning with aftermarket camshafts, refer to this authoritative resource on advanced AVCS tuning strategies.

Vehicle Fitment & Platform Suitability

The BC0620 camshaft set is engineered specifically for the Subaru EJ257 and EJ255 engine platforms. This encompasses a range of high-performance Subaru models, but it is critical to verify engine code and ensure all supporting modifications are in place before purchase and installation.

Primary Applications Include:

• Subaru WRX STI (2004-2021) with EJ257 engine
• Subaru WRX (2006-2014) with EJ255 engine
• Subaru Forester XT (2004-2018) with EJ255/EJ257
• Subaru Legacy GT (2005-2012) with EJ255 engine
• Other compatible EJ25 turbo variants (e.g., Saab 9-2X Aero) with verified engine architecture

Note: Always confirm the specific engine designation in your vehicle. These cams are intended for use in engines that have been fully built with forged pistons, aftermarket connecting rods, and an upgraded valvetrain. They are not suitable for stock-internals engines or daily drivers without extensive supporting modifications.

Installation Considerations & Tuning Imperatives

Installing the BC0620 camshafts is a precision operation that should only be undertaken by experienced technicians familiar with Subaru boxer engine assembly. Key steps include verifying clearances between valves and pistons (P2V), ensuring proper valve spring installed height and pressure, and setting timing with meticulous accuracy. The use of adjustable cam gears is highly recommended to allow the tuner to dial in the exact intake and exhaust centerlines for your specific combination of turbo, headwork, and fuel. Once installed, the vehicle must be tuned by a professional using a capable engine management system (e.g., Cobb Accessport with Pro Tuning, Haltech, Link ECU). The tune must account for the altered volumetric efficiency, recalibrate AVCS maps, and adjust fuel and ignition timing accordingly. A baseline dyno session followed by street or track refinement is necessary to extract safe, maximum performance.

Technical Specifications: BC0620 Camshaft Set