BC0905 – Polaris XP 1000 (14-up) Stage 5 Race Only Camshafts (pair)

In the arena of UTV competition, where victory is measured in hundredths of a second and engine integrity is non-negotiable, the valve train is the final command link between ECU strategy and explosive cylinder pressure. The Brian Crower BC0905 Stage 5 Race Only camshaft set represents the apex of this critical connection, engineered exclusively for the Polaris XP 1000 platform (2014 and newer). This is not a modification; it is a fundamental re-engineering of the engine’s volumetric efficiency and personality. Designed for all-out race applications—be it desert, short-course, or hill climb—these billet camshafts deploy an ultra-aggressive lobe profile to violently maximize lift and duration, forcing the 999cc twin-cylinder engine to ingest and expel atmosphere at a rate far beyond OEM parameters. For the builder whose machine is tethered solely to the pursuit of maximum power above 6,500 RPM, the BC0905 is the definitive component to unlock the final, ferocious segment of your engine’s performance envelope.

Engineering Analysis: The Stage 5 “Race Only” Lobe Profile

To understand the BC0905 is to understand the physics of extreme valve events. Brian Crower’s “Stage 5” nomenclature denotes a profile designed with absolute peak horsepower as the singular goal, deliberately sacrificing low-speed manners and idle quality. Crafted from 8620 billet steel, each cam is meticulously machined with an asymmetric lobe design. The intake side features a radically accelerated opening ramp to get the valve to its peak lift point as quickly as possible, maximizing the area under the lift curve—a direct correlate to airflow. The exhaust lobe is engineered with sustained high-lift duration to aggressively scavenge spent combustion gases, reducing pumping losses and minimizing cylinder contamination for the incoming charge. This profile creates significant overlap, the period where both intake and exhaust valves are open simultaneously. At high RPM, this exploits inertial tuning and exhaust pulsing to effectively “supercharge” the cylinder with fresh air/fuel mixture. The resulting power curve is notoriously peaky, delivering a monumental surge of power in a narrow, high-RPM band that demands a complementary, fully-built engine and expert tuning.

Demystifying Camshaft Specifications: Lift, Duration, and LSA

The performance language of the BC0905 is written in its key specifications, which dictate the engine’s new operational character.

• Aggressive Lift Increase: The camshaft achieves significantly higher valve lift compared to stock and milder aftermarket grinds. This elevated lift physically opens the valve farther, presenting a larger curtain area for airflow past the valve seat. When paired with ported cylinder heads and oversized valves, this becomes the primary mechanism for increasing the engine’s maximum airflow capacity (CFM).
• Extended Duration: The duration—measured in degrees of crankshaft rotation that the valve remains off its seat—is substantially increased. This allows more time for the cylinder to fill at high RPM, where the inertial dynamics of the intake charge become favorable. However, this extended open period is what degrades low-end vacuum and torque, cementing the “race only” designation.
• Narrowed Lobe Separation Angle (LSA): The LSA, the centerline spacing between the intake and exhaust lobe peaks, is tightened on the BC0905. A narrower LSA increases overlap, amplifying the scavenging effect and raising peak cylinder pressure at the expense of idle stability and emissions. This is a calculated trade-off for competition engines where off-idle behavior is irrelevant.

For a deeper dive into the interplay between these specifications and engine harmonics, consider this resource on camshaft lobe separation angle and valvetrain dynamics.

Installation & Valvetrain Compatibility Requirements

The installation of the BC0905 camshafts is a precision operation that mandates supporting modifications. The stock valve springs are incapable of managing the increased lift, aggressive ramp speeds, and elevated RPM ceiling. Failure to upgrade the entire valvetrain will result in valve float, catastrophic engine failure, and severe personal injury. A mandatory complement includes:

• High-pressure dual or beehive valve springs with compatible titanium retainers.
• Chromoly or tool steel pushrods to resist deflection under high spring pressure.
• Performance lifter kits, often of the roller variety, to reduce friction and follow the aggressive lobe profile reliably.
• Professional degreeing of the camshafts during installation is not recommended; it is required to verify exact timing events and ensure the engine performs to the cam designer’s intent.

Furthermore, this cam profile will necessitate comprehensive fuel and ignition remapping. The engine’s increased volumetric efficiency and altered vacuum signature demand significant adjustments to fuel tables and spark advance to realize the power gains safely and effectively.

Vehicle Fitment & Application

The BC0905 is engineered as a direct-fit component for specific Polaris RZR XP 1000 models utilizing the ProStar 1000 H.O. engine. Correct application is critical for mechanical and performance integrity.

Primary Fitment:

• Polaris RZR XP 1000 (2014, 2015, 2016, 2017, 2018)
• Polaris RZR XP 1000 EPS Models within the above model years

Critical Note: This camshaft set is designed for naturally aspirated, race-only applications. It is not compatible with turbocharged or supercharged setups without extensive, expert-level tuning modifications that account for the profound change in cylinder pressure dynamics. Use in a forced induction application without such tuning will almost certainly lead to pre-ignition or detonation.

Technical Specifications Table

Conclusion: The Ultimate Power Commitment

The Brian Crower BC0905 Stage 5 Race Only Camshafts are the definitive choice for the racer who has exhausted all other avenues of naturally aspirated power extraction. They represent a commitment to an engine built from the ground up for a singular purpose: dominating in a specific, high-RPM power band. This upgrade is intensive, requiring a holistic approach to engine building, precision installation, and expert tuning. The reward, however, is an engine with a transformed, hyper-aggressive personality capable of producing the absolute maximum horsepower possible from the ProStar 1000 platform’s architecture. This is not a part for the casual enthusiast; it is the final, calculated stroke for the competitor who views their machine as a weapon for the podium.