BC6619 – Subaru BRZ, Scion FR-S, Toyota GT86 I-Beam Connecting Rods w/ARP2000 Fasteners

In the relentless pursuit of power and reliability, the connecting rod stands as the definitive linchpin between piston and crankshaft, a component upon which the entire rotating assembly’s integrity hinges. For the Subaru BRZ, Scion FR-S, and Toyota GT86 platform, powered by the revered FA20/FA24 D-4S engine, the stock powdered-metal rods represent a calculated compromise for mass production, not for the extreme cylinder pressures of forced induction or high-RPM, naturally aspirated builds. The Brian Crower BC6619 I-Beam Connecting Rod set, meticulously engineered from 4340 chromoly steel and secured with legendary ARP2000 cap screws, is the unequivocal upgrade for engineers and builders who prioritize unyielding strength and precision. This is not merely a part; it is a fundamental re-engineering of a critical stress point, transforming your FA20’s bottom end from a potential failure point into a foundation capable of supporting well over 500+ wheel horsepower with absolute confidence.

Material & Manufacturing: The 4340 Chromoly Foundation

The genesis of the BC6619’s superiority lies in its core material: aircraft-quality 4340 chromoly steel. This nickel-chromium-molybdenum alloy is the undisputed standard for high-stress performance components, offering an exceptional balance of ultimate tensile strength, fatigue resistance, and ductility. Unlike the stock sintered forged powdered metal rods, 4340 chromoly retains its structural integrity under repeated high-load cycles, resisting the micro-fractures that lead to catastrophic failure. Brian Crower sources only premium-grade domestic 4340 alloy, subjecting each billet to rigorous spectrographic analysis to verify chemistry before the manufacturing process even begins.

The BC6619 rods are manufactured using the precision CNC billet machining process. Starting from a solid bar of 4340 chromoly, the rods are machined to their final form, allowing for grain structure that follows the contour of the rod, optimizing strength throughout its entire profile. This method provides superior consistency and allows for tighter weight-matching tolerances compared to traditional forging, where material grain flow can be less predictable. Each rod is then subjected to a multi-stage heat-treating and thermal cycling process, which includes carburizing for a hardened, wear-resistant outer surface and a specific tempering procedure to achieve a core hardness of Rockwell C 38-42. This creates a rod that is incredibly tough on the outside to resist bearing wear and galling, yet maintains a slight degree of malleability at its core to absorb shock loads without becoming brittle.

Engineering the I-Beam: A Design for Ultimate Rigidity

The choice of an I-beam design for the BC6619 is a deliberate engineering decision targeting maximum beam strength and longitudinal rigidity. The I-beam profile, reminiscent of structural steel used in construction, places material precisely where it is needed to resist bending and buckling forces under combustion load. The broad, flat flanges of the “I” provide exceptional resistance to the compressive forces driving the piston down, while the central web manages the tensile forces as the piston is pulled back up the bore during the exhaust stroke. For a high-revving, oversquare engine like the FA20, which sees significant piston acceleration, this rigidity is non-negotiable. It prevents rod flex, which can lead to premature bearing failure, uneven cylinder wear, and a loss of power as energy is wasted deforming the rod instead of being transmitted to the crankshaft. A deeper analysis of connecting rod beam design and stress dynamics can be found in this authoritative technical article on connecting rod selection.

ARP2000 Fasteners: The Critical Interface

Even the world’s strongest connecting rod is only as reliable as the bolts that clamp its cap to the body. Brian Crower eliminates this variable by including industry-standard ARP 2000 cap screws as part of the BC6619 kit. The ARP2000 alloy is a premium, strain-hardened material that achieves a tensile strength of 220,000 psi, far exceeding the capability of OEM or generic fasteners. These are not merely “bolts”; they are precision-engineered studs that are installed into the rod body, with a nut torqued onto them to pull the cap into place. This design provides a more even clamp load distribution across the rod and cap interface compared to traditional bolts, crucial for maintaining perfect big-end bore roundness under extreme loads. Each fastener is lubricated with ARP’s proprietary Ultra-Torque fastener lubricant, ensuring the specified torque reading accurately translates to the proper clamp load without friction-induced error. The inclusion of these fasteners represents a complete, ready-to-install solution that leaves nothing to chance.

• Uncompromising Material: CNC-machined from premium 4340 chromoly steel billet for optimal grain structure and consistency.
• Engineered for Rigidity: I-beam design maximizes strength-to-weight ratio and resists bending under high cylinder pressure and RPM.
• Complete Fastener Solution: Includes legendary ARP 2000 cap screws (220,000 psi tensile) and Ultra-Torque lubricant for a perfect, reliable clamp.
• Precision Balanced: Each set is weight-matched to within a 2-gram tolerance, ensuring a smooth, balanced rotating assembly.
• Maximum Durability: Multi-stage heat-treating and carburizing process yields a tough, wear-resistant surface with a ductile core.
• High-Performance Clearances: Features a precision .827-inch wrist pin bore and is designed for use with performance crankshaft bearings.
• Proven Power Capacity: Provides a reliable foundation for forced induction and high-RPM builds exceeding 500+ wheel horsepower.

Technical Specifications & Installation Considerations

Precision is paramount. The BC6619 rods are manufactured to exacting specifications that both match OEM critical dimensions and incorporate enhancements for performance use. The center-to-center length is held to a strict tolerance to maintain proper piston deck height and compression ratio. The small end features a pressed wrist pin design for secure retention, compatible with OEM or aftermarket pistons, while the large end is sized for standard 2.0081-inch journal diameter crankshafts. Proper installation is not optional; it is a requirement. This includes having the rod big ends professionally sized with a bore gauge after the ARP fasteners are torqued to spec, as the clamping force will slightly distort the bore from its “free” state. Pair these rods with a matched set of performance crankshaft bearings and ensure all clearances are verified during assembly.

Vehicle Fitment: Precision Application

The BC6619 is engineered as a direct, no-compromise replacement for the factory connecting rods in the following vehicles. It is imperative to confirm all engine specifications, including year and displacement, prior to purchase, as subtle changes between model years may exist. These rods are designed for the FA20 and FA24 horizontally-opposed (boxer) engines.

Subaru: BRZ (2013-2020 for FA20, 2022+ for FA24 – verify displacement).
Toyota: GR86 (2022+ for FA24 – verify displacement), GT86 (2012-2020).
Scion: FR-S (2013-2016).

Note: This is a performance component intended for engine rebuilding by a qualified machinist or engine builder. Installation requires complete engine disassembly, machining expertise for final big-end sizing, and precise clearance checking. Always refer to the manufacturer’s installation instructions and use a professional torque wrench calibrated in inch-pounds for the ARP fasteners.

The Final Verdict: Building an Unbreakable Foundation

The Brian Crower BC6619 I-Beam Connecting Rod set with ARP2000 fasteners represents the definitive solution for the serious FA20/FA24 builder. It transcends the category of a simple upgrade, serving as a fundamental re-engineering of a critical engine component using the best materials and design principles available. By selecting a billet 4340 chromoly construction, the optimal I-beam profile, and including the gold-standard in fastener technology, Brian Crower has created a component that removes the connecting rod as a variable in the high-performance equation. Whether your build targets relentless turbocharged thrust, high-RPM naturally aspirated track performance, or simply the absolute peace of mind that comes with an over-engineered bottom end, the BC6619 provides the unyielding structural foundation required to realize that goal reliably. This is the investment that protects all others.