BC9913 – Polaris ProXP / Turbo R CNC Cylinder Head – Big Port 38.8mm/33mm Valves

Engineered Dominance: The Brian Crower BC9913 CNC Cylinder Head for Polaris Pro XP & Turbo R

In the realm of high-performance UTV engines, airflow is the ultimate currency. The factory cylinder head, while reliable, represents a significant bottleneck for enthusiasts and competitors seeking maximum horsepower and torque. The Brian Crower BC9913 CNC Cylinder Head is not an incremental upgrade; it is a complete re-engineering of the combustion chamber’s architecture, designed specifically for the Polaris Pro XP 1000 and Turbo R platforms. Utilizing state-of-the-art 5-axis CNC machinery, this component transforms the ProStar 1000 H.O. and Turbo R engines from potent factory units into veritable powerplants, unlocking latent potential through meticulous airflow management and superior thermal dynamics. For the rider who understands that performance is measured in cubic feet per minute (CFM) and combustion efficiency, the BC9913 is the definitive foundation for any serious build, from a aggressive trail machine to a podium-chasing race vehicle.

Every contour of the BC9913’s intake and exhaust ports has been digitally optimized and machined with tolerances measured in thousandths of an inch. This Big Port design is centered around massive 38.8mm intake and 33mm exhaust valves, crafted from high-grade stainless steel to withstand extreme temperatures and RPM. The increased valve diameter provides a substantial increase in flow area, but the true genius lies in the port velocity and swirl profile. Brian Crower’s engineers have sculpted the runners to maintain high airspeed at low lift, improving throttle response, while maximizing total flow at high lift for peak horsepower. This precise calibration ensures you gain power across the entire RPM band, not just at the rev limiter.

Precision Machining and Uncompromising Materials

The “CNC” designation is not merely marketing jargon. Unlike cast or hand-ported heads, the BC9913 is machined from a premium-quality aluminum casting in a fully controlled, automated process. This guarantees absolute consistency from one cylinder head to the next—a critical factor for engine builders seeking repeatable, reliable performance. The combustion chambers are CNC-machined to a precise volume, ensuring uniform compression ratios across all cylinders, which is paramount for engine balance and detonation control under boost or high compression.

The valve seats are precision-cut and blended seamlessly into the port walls, eliminating any disruptive transitions that can cause turbulence and flow separation. This attention to detail extends to the surface finish; a specific texture is applied to the intake ports to promote fuel atomization, while the exhaust ports are smoothed to minimize heat retention and expedite exhaust gas evacuation. Paired with the included high-performance valve springs and titanium retainers (designed for aggressive camshaft profiles), the BC9913 is a complete, ready-to-assemble system engineered for durability at sustained high output.

Key Performance Benefits of the BC9913 Big Port Head

• Substantial Horsepower & Torque Gains: The optimized port geometry and larger valves facilitate a dramatic increase in airflow, directly translating to more power. Expect significant gains, particularly in the mid-to-top RPM range, with properly supporting modifications.
• Enhanced Throttle Response and Reduced Turbo Lag (Turbo R): Improved low-lift flow characteristics mean the engine breathes more efficiently at lower RPMs. This results in crisper throttle response and, for turbocharged applications, a noticeable reduction in spool time as exhaust energy is utilized more effectively.
• Superior Thermal Management: The high-quality aluminum alloy and efficient design dissipate heat more rapidly than the stock casting. This maintains a more stable combustion chamber temperature, reducing the risk of pre-ignition and allowing for more aggressive tuning.
• Foundation for Forced Induction and High-Compression Builds: This head is designed to handle the increased demands of turbocharging, supercharging, or high-compression naturally aspirated setups. The robust valve train and efficient chamber are built for the elevated pressures and temperatures.
• Maximum Tuning Potential and Consistency: Provides a stable, high-flow platform that allows your tuner to extract every ounce of performance safely. The CNC precision ensures your engine’s performance is repeatable and reliable.

Vehicle Fitment: Application-Specific Engineering

The Brian Crower BC9913 is engineered as a direct-replacement component for specific Polaris models to guarantee proper fitment with factory and aftermarket intake/exhaust manifolds, head gaskets, and mounting hardware. It is not a universal “one-size-fits-most” part. Always verify your specific engine model and year before purchasing.

Primary Fitment:

• Polaris Pro XP 1000 (Non-Turbo, ProStar 1000 H.O. Engine) – All Years

• Polaris Turbo R (ProStar 1000 Turbo R Engine) – All Years

Note on Compatibility: This cylinder head is designed for the 4-stroke, twin-cylinder ProStar 1000 platform. It is not compatible with earlier 900 models or the RZR XP 1000 models using the different ProStar 1000 engine architecture. Installation requires mechanical expertise, including proper valve lash adjustment and head torque sequence following factory service specifications.

Technical Specifications & Design Data

The Final Verdict: The Pinnacle of Bolt-On Airflow

The Brian Crower BC9913 CNC Cylinder Head represents a calculated investment in the thermodynamic heart of your Polaris Pro XP or Turbo R. It addresses the fundamental limitations of the factory casting with surgical precision, offering gains that are tangible from the driver’s seat. When combined with complementary upgrades such as a performance camshaft, high-flow intake, and a professional tune, the BC9913 becomes the cornerstone of a transformative powertrain overhaul. This is not a component for the casual rider; it is engineered for those who demand the highest level of mechanical performance and understand that dominating the dunes, the trails, or the track begins with mastering the science of airflow. For a deeper technical dive into how cylinder head port geometry influences engine performance, consider reading this authoritative resource on cylinder head porting and airflow principles from MotorTrend.