BC4910N – New Polaris XP Turbo or XP1000 Crankcase w/ Linebore, Shuffle Pin, ARP main studs and King mains (no core exchange)

In the relentless pursuit of power and reliability in high-performance UTV engines, the foundation is everything. The BC4910N Crankcase Assembly from Brian Crower represents a quantum leap in bottom-end integrity for the Polaris XP Turbo and XP1000 platforms. This isn’t a repaired or reconditioned unit; it’s a new, engineered-from-the-ground-up assembly designed to eliminate the inherent weaknesses of the stock casting. Incorporating a precision linebore, a factory shuffle pin, legendary ARP main studs, and durable King XP main bearings, the BC4910N transforms your engine’s core into an unyielding bedrock capable of supporting extreme horsepower and rotational forces. For builders targeting forced induction overhauls, serious big-bore stroker applications, or simply demanding absolute reliability, this crankcase is the non-negotiable starting point.

Engineering the Unbreakable Foundation: Core Technologies

Brian Crower’s approach with the BC4910N addresses the systemic failure points of the OEM ProStar crankcase through precision machining and superior component selection. The stock main bore can distort under high cylinder pressure and the immense clamp load of performance head studs, leading to bearing misalignment and premature failure. BC’s solution is a CNC precision linebore, which ensures all main bearing saddles are perfectly co-axial and to a consistent, exacting diameter. This guarantees optimal bearing crush and alignment, critical for maintaining proper oil clearances and stabilizing the crankshaft under extreme loads. The integration of the factory shuffle pin is retained, a crucial feature that locates the crankcase halves with absolute accuracy to maintain this perfect alignment during assembly and operation.

Component Synergy: ARP Studs & King Bearings

The synergy between components is where the BC4910N truly excels. The assembly is fitted with ARP main studs, the industry gold standard for fastener technology. Manufactured from 8740 chrome-molybdenum steel, heat-treated, and rolled-threaded for superior tensile strength and fatigue resistance, these studs provide a consistent, massive clamp load that prevents crankcase walk and bore distortion. Paired with these studs are King XP Series main bearings. King’s tri-metal construction—with a steel backing, copper-lead intermediate layer, and electro-plated babbitt overlay—offers exceptional embedability, conformability, and fatigue strength, far surpassing OEM specifications. This combination creates a main bearing environment of unparalleled stability and durability.

Definitive Advantages of the BC4910N Assembly

• Eliminates Core Dependency & Hidden Damage: Sold as a complete new assembly (no core exchange required), you receive a guaranteed perfect foundation without the risk of hidden cracks, porosity, or prior damage inherent in used cores.
• Absolute Main Bore Alignment: The precision linebore process ensures perfect crankshaft alignment, reducing parasitic drag, ensuring consistent oil pressure, and preventing localized bearing wear.
• Unmatched Clamping Force & Stability: ARP main studs provide a superior seal and eliminate crankcase flex under high cylinder pressures, a common failure point in boosted applications.
• Enhanced Bearing Durability: King XP main bearings offer significantly higher load capacity and fatigue life than OEM, directly contributing to extended engine life under stress.
• Simplified, Guaranteed Build Process: Arrives as a ready-to-assemble, matched system. No need to source, machine, and verify separate components, saving time and ensuring compatibility.
• Supports Extreme Horsepower Goals: The reinforced foundation is mandatory for builds involving turbocharger upgrades, nitrous oxide, or large-displacement stroker crankshafts.

Precise Vehicle Fitment

The BC4910N is engineered specifically for the Polaris ProStar 1000 platform. Its application is critical for vehicles subjected to performance modifications where bottom-end integrity is paramount. Always verify your specific model year and engine code, but primary fitment includes:

Primary Application: Polaris RZR XP 1000 (all models and years utilizing the ProStar 1000 engine).
High-Performance Target Application: Polaris RZR XP Turbo / Turbo S (2018-2023) for builds replacing or preempting the stock crankcase.
Note: This assembly is for the crankcase only. All other rotating assembly components, crankshaft, pistons, cylinders, and heads must be sourced separately. It is designed for use by experienced engine builders or performance shops familiar with ProStar engine assembly procedures and clearances.

Technical Specifications & Details

The Non-Negligible Upgrade for Serious Builds

Choosing the BC4910N is a definitive decision to prioritize longevity and power potential over short-term cost savings. In performance engine building, the sum is only as strong as its weakest part. While bolt-on modifications can increase power, they exponentially increase stress on the engine’s foundation. The stock crankcase, often with unknown service history and manufacturing variances, becomes the predictable point of failure. This Brian Crower assembly eradicates that variable. For further technical reading on the critical importance of main bore alignment and fastener technology in high-stress engines, consider this resource on main bore alignment principles. The BC4910N isn’t just a part; it’s an investment in the structural integrity of your entire high-performance Polaris build, ensuring that the power you make is fully supported from the ground up.