BC5910B – Brian Crower Fully Balanced Crankshaft for Polaris RZR XP Turbo (2016-Up)

In the high-stakes arena of forced-induction side-by-side performance, the crankshaft is the uncompromising heart of the engine—a component where failure is not an option. The Brian Crower BC5910B Fully Balanced Stock Stroke Crankshaft is engineered not as an afterthought, but as a foundational upgrade for the Polaris RZR XP Turbo platform. Designed for the builder who demands absolute rotational integrity, this 68mm stroke, 270° crank pin billet masterpiece transforms the factory rotating assembly from a potential liability into a paragon of durability and power delivery. For those pushing boost pressures, engine RPM, and vehicle dynamics beyond factory limits, this crankshaft is the definitive solution for achieving a robust, balanced, and reliable rotating assembly.

Engineering Superiority: The Foundation of Forced-Induction Reliability

Factory crankshafts are manufactured to a price point and a generalized durability standard, often leaving minimal safety margin for modified, high-output applications. The BC5910B addresses every inherent weakness. Crafted from premium 4340 chromoly billet steel, it offers a dramatic increase in tensile and yield strength over the stock casting. This material choice is critical for resisting the immense torsional and bending stresses generated by turbocharged horsepower and the violent load changes encountered in off-road racing. The fully balanced configuration is not merely a factory reprise; each unit is precision balanced to a tolerance that eliminates destructive harmonics, reduces parasitic vibration, and allows the engine to rev more freely and with significantly less internal stress. This process ensures that the tremendous force of each power stroke is converted into smooth, usable rotation at the output sprocket.

Core Design Benefits & Technical Advantages

The BC5910B integrates several key design philosophies that directly translate to performance and longevity in the harsh RZR environment.

• 270° Crank Pin Configuration: This is the heart of its character. Unlike a traditional 180° pin setup, the 270° firing order creates a distinct, lumpier idle and alters the engine’s power pulse frequency. This results in enhanced tractability and low-end torque, providing superior chassis control and immediate throttle response in technical terrain—a significant advantage for both high-speed desert racing and precise rock crawling.
• 4340 Billet Steel Construction: CNC-machined from a single forging, billet steel provides a continuous grain flow, eliminating the potential for porosity, inclusions, or weak points found in castings. This yields a crankshaft with superior fatigue resistance and impact strength, essential for surviving piston detonation events or sudden driveline shock.
• Fully Balanced Assembly: Brian Crower’s balancing process accounts for the entire rotating assembly (crankshaft, rods, pistons, and flywheel). This meticulous balance minimizes NVH (Noise, Vibration, Harshness), reduces bearing load, and prolongs the life of every component in the bottom end and valvetrain.
• Stock 68mm Stroke: Maintaining the factory stroke allows for a direct replacement without requiring custom pistons or re-calibration of the vehicle’s ECU for displacement changes. It is the ideal choice for builders focusing on boost, head work, and RPM to make power, ensuring compatibility and simplifying the build process.
• Precision Machined Journals & Oilways: Every journal surface is micro-finished to a mirror polish, promoting optimal oil film retention and reducing friction. Oil passages are meticulously deburred and chamfered to ensure unrestricted oil flow to the critical rod and main bearings under high-RPM, high-G conditions.

Technical Specifications & Fabrication Details

Understanding the precise metrics of this component is crucial for integration into any performance or endurance build. The BC5910B is a testament to application-specific engineering.

The 270° crank pin design is a performance differentiator. To understand the profound impact of crank pin angle on engine character and power delivery in performance engines, this technical resource on crankshaft fundamentals provides an excellent deep dive into the physics and application.

Vehicle Fitment: Precision Application

The BC5910B is engineered as a direct, bolt-in replacement for the stock crankshaft in the following specific models. It is imperative to verify engine code and model year before purchase.

• Polaris RZR XP 1000 Turbo: All model years from 2016 through the present production run.
• Polaris RZR XP 4 1000 Turbo: All model years from 2016 through the present production run.
• Note on Compatibility: This crankshaft is designed specifically for the turbocharged ProStar 1000 engine. It is not compatible with naturally aspirated RZR XP 1000 models or earlier Turbo models (pre-2016).

The Critical Role in a Performance Build

Installing the BC5910B crankshaft is not merely a repair; it is a strategic upgrade that unlocks the potential of other modifications. A fortified bottom end allows tuners to safely explore higher boost thresholds and more aggressive ignition timing without fear of catastrophic failure. The improved balance reduces overall engine stress, which in turn protects cylinder heads, valvetrains, and even transmission components from vibration-induced wear. When paired with quality forged connecting rods and pistons, this crankshaft creates a rotating assembly capable of supporting well over 200+ horsepower reliably—a necessity for those competing in unlimited turbo classes or demanding extreme durability from their trail machine. It is the silent, spinning guarantor of your engine investment.

In conclusion, the Brian Crower BC5910B Fully Balanced Crankshaft represents the pinnacle of rotational mass engineering for the Polaris XP Turbo platform. It delivers the material strength, precision balance, and innovative 270° firing order needed to harness and sustain serious horsepower. For the builder who views reliability as a performance feature, this component is not an option; it is an essential, non-negotiable foundation for any high-output or competition-oriented RZR build.