BC6135 – Brian Crower ProH2K Connecting Rods for Mitsubishi 4B11 with ARP2000 Fasteners

For the engineer, builder, or driver pushing the limits of the Mitsubishi 4B11 powerplant—found in the revered Lancer Evolution X and other platforms—the connecting rod represents the critical pivot point between rotational force and linear motion. It is the component that must withstand the apocalyptic forces of high-boost combustion and punishing RPM, translating piston energy into crankshaft rotation without failure. Standard rods are the predictable point of catastrophic yield in a built engine. The BC6135 ProH2K Connecting Rod kit from Brian Crower, outfitted with industry-standard ARP2000 Fasteners, is engineered to eliminate that variable. This is not an upgrade; it is a foundational re-engineering of the 4B11’s reciprocating assembly for absolute reliability under extreme horsepower and rotational velocity. Constructed from premium 4340 chromoly steel and finished with a proprietary ProH2K treatment, these rods are the definitive solution for builds targeting 800+ wheel horsepower and sustained high-RPM operation, transforming the engine’s lower end from a potential liability into an asset of unshakeable strength.

Engineering for the Apocalypse: ProH2K 4340 Chromoly Construction

The core philosophy behind the BC6135 rod is intelligent over-engineering. Brian Crower starts with a forged billet of SAE 4340 chromoly steel, a nickel-chromium-molybdenum alloy renowned for its exceptional tensile strength, superior fatigue resistance, and admirable toughness. This material choice is the first and most critical departure from OEM or lesser-quality aftermarket rods. The forging process aligns the metal’s grain structure to follow the rod’s contours, creating a naturally stronger component resistant to the cyclical loading and unloading forces that cause fatigue failure. However, the “ProH2K” designation signifies the next stage: a proprietary Hydrogen Embrittlement Relief and Stress Relief process. This advanced treatment meticulously removes residual machining stresses and potential hydrogen embrittlement—a common cause of delayed, sudden fracture in high-strength steels. The result is a connecting rod with a more stable, predictable, and durable molecular structure, capable of handling the intense cylinder pressures generated by large turbochargers and aggressive tuning profiles.

The Fastener Standard: ARP 2000 Cap Screws

The strongest rod beam is only as reliable as its weakest point, which is invariably the joint between the rod and cap. Brian Crower eliminates this vulnerability by including ARP 2000 Wave-Loc® Cap Screws as standard equipment. ARP’s 2000-series fasteners are made from a proprietary 8740 chromoly steel alloy, heat-treated to achieve a 200,000 psi tensile strength. The Wave-Loc feature on the threads creates a prevailing torque lock, preventing fastener loosening under extreme vibration without the need for chemical thread lockers that can affect clamp load accuracy. These fasteners are torqued using the industry-standard “torque-plus-angle” method, ensuring a perfectly consistent and precise clamp load across all four rods. This guarantees perfect cap-to-rod alignment, maintaining the critical bore roundness and bearing crush essential for oil film stability and longevity. In essence, the inclusion of ARP2000 fasteners signifies that every aspect of the BC6135 kit is built to a motorsport standard.

Precision Application: Vehicle Fitment & Compatibility

The BC6135 kit is engineered as a direct, precision-fit replacement for the OEM connecting rods in specific Mitsubishi 4B11 engines. Correct fitment is paramount for achieving the designed performance and reliability. These rods are intended for use with standard wrist pin diameters and crankshaft journals, but always verify clearances during assembly.

Primary Vehicle Fitment:

• 2008-2015 Mitsubishi Lancer Evolution X (4B11T Engine)
• Mitsubishi 4B11 Engine Platforms in Road Race, Time Attack, and High-Performance Street Applications

Critical Installation Note: These performance connecting rods require professional installation by a qualified engine machinist and builder. Essential steps include:

• Precision weighing and balancing of the entire rotating assembly (rods, pistons, pins, rings).
• Verification and adjustment of side clearance and bearing clearances with precision measuring tools.
• Final torque of ARP fasteners using ARP’s specified lubricant and torque-plus-angle procedure.

Always consult with your engine builder and refer to the latest Brian Crower installation documentation for specific tolerances and procedures. For a deeper technical dive into connecting rod metallurgy and design theory, resources like EngineLabs’ connecting rod tech article provide valuable context.

Technical Specifications & Dimensions

The Definitive Advantage: Why Choose the BC6135 ProH2K Rods?

Selecting the BC6135 kit is a decision to build with confidence. The advantages are tangible and critical for any serious performance or competition engine.

• Unmatched Strength-to-Weight Ratio: The 4340 chromoly forging provides immense beam strength without the excessive mass of lesser materials, reducing reciprocating weight for improved engine response and higher safe RPM limits.
• ProH2K Fatigue Resistance: The proprietary treatment directly targets and mitigates the primary failure modes of high-strength connecting rods, offering peace of mind for high-boost and high-RPM applications.
• Turn-Key Fastener Solution: Including ARP2000 fasteners ensures the rod’s theoretical strength is fully realized in practice with a perfect, reliable joint. It eliminates guesswork and sourcing of separate components.
• Precision Manufacturing: Every rod is CNC-machined to exacting tolerances, ensuring consistent weight and dimensions right out of the box, which simplifies the balancing process and guarantees uniform performance across all cylinders.
• Proven Track Record: Brian Crower components are staples in national and world championship-winning motorsport programs, offering a level of proven performance that theoretical data alone cannot provide.

For the individual committed to extracting maximum performance and ultimate durability from the Mitsubishi 4B11 platform, the BC6135 ProH2K Connecting Rod set is a non-negotiable component. It represents a synthesis of premium material science, advanced manufacturing processes, and proven motorsport hardware. This kit provides the robust foundation upon which a truly formidable, high-horsepower engine is constructed, allowing you to focus on tuning and power generation with the absolute certainty that your rotating assembly is built to endure it.