BC0042-2 – Honda K20A/K20Z Stage 2 Camshafts – Normally Aspirated/High Boost

For the dedicated builder seeking to unlock the definitive performance character of the Honda K20A and K20Z series engines, the Brian Crower BC0042-2 Stage 2 Camshafts represent a critical path from potent street machine to full-bore performance powerhouse. Engineered for the enthusiast who understands that volumetric efficiency is the cornerstone of power, this camshaft set is a precision-machined key to transforming your engine’s breathing capabilities. Whether deployed in a high-compression, naturally aspirated build where every last horsepower is wrung from atmospheric pressure, or in a high-boost forced induction application where controlling the charge is paramount, the BC0042-2 profile is calculated to deliver substantial, usable gains across the power band. This is not a generic “one-size-fits-most” grind; it is the result of extensive dyno testing and track validation, offering a aggressive yet streetable profile that demands proper supporting modifications and tuning to realize its full, formidable potential. Installing these cams signals a commitment to serious performance, moving beyond bolt-ons and into the realm of engineered engine transformation.

Engineering Philosophy: The Science of the Stage 2 Profile

The “Stage 2” designation is often misused, but with Brian Crower, it signifies a specific and purposeful performance threshold. The BC0042-2 camshafts are designed for engines with significant internal work—think upgraded valvetrain, increased compression, optimized head porting, and a tailored exhaust system. The profile features increased lift and duration over stock and milder “Stage 1” grinds, but retains a focus on broad power delivery and mechanical sympathy. The increased duration holds the valves open longer, allowing a greater volume of air/fuel mixture into the cylinder and more time for exhaust gases to exit. The heightened lift raises the valves farther off their seats, maximizing the flow area through the port at the critical point of highest piston velocity. This combination is tuned to shift the power band higher in the RPM range while mitigating low-RPM torque loss through careful lobe design. The cams are machined from premium-grade steel billet, heat-treated using a proprietary process for exceptional surface hardness and core durability, ensuring they withstand the relentless stresses of high-RPM operation and aggressive valve spring pressures.

Strategic Benefits for NA and Boosted Applications

The BC0042-2 profile exhibits a unique duality, making it a favored choice for two distinct build paths. In Normally Aspirated (NA) applications, the camshafts work synergistically with high-compression pistons and ported heads to create an engine that breathes deeply and efficiently. The power gains are realized through sheer volumetric efficiency, producing a fierce, linear power band that builds relentlessly to a soaring redline. For High-Boost Forced Induction applications, the extended overlap period (where both intake and exhaust valves are open slightly at the same time) can be strategically leveraged. During this period, the outgoing exhaust pulse can help draw in the incoming fresh charge, effectively “scavenging” the cylinder. This is particularly beneficial in turbocharged setups, as it can help reduce pumping losses and lower exhaust backpressure, translating to faster spool and a more efficient combustion cycle. A comprehensive resource on optimizing K-series valve events for forced induction can be found in this guide to camshaft fundamentals from industry experts.

Tangible Performance Advantages

Choosing the BC0042-2 camshafts is an investment in measurable and visceral performance improvements. When paired with the required supporting modifications and professional tuning, users can expect:

• Substantial Peak Power Gains: Depending on the full complement of engine modifications, gains of 25-50+ wheel horsepower are achievable, moving the power peak effectively into the 7500-8500 RPM range.
• Expanded and Elevated Power Band: The power curve is transformed, with a strong, building mid-range that erupts into a top-end rush, perfect for road racing, time attack, or spirited street driving.
• Enhanced Engine Sound and Character: The aggressive lobe profile produces the iconic, lumpy idle associated with high-performance engines, a direct auditory signal of the potential within.
• Improved Cylinder Scavenging: The optimized overlap promotes cleaner evacuation of exhaust gases, leading to denser air/fuel charges and more consistent combustion.
• Foundation for Future Modifications: This camshaft set establishes a performance baseline that can effectively support future upgrades like individual throttle bodies or larger turbochargers.

Detailed Vehicle Fitment & Installation Prerequisites

Vehicle Fitment: The BC0042-2 camshaft set is engineered specifically for the Honda/Acura K20A, K20A2, K20A3, K20Z1, K20Z3, and related variants. Direct fitment includes popular platforms such as the:

• Honda Civic Si (2006-2011, FA5/FG2 with K20Z3)
• Acura RSX Type-S (2002-2006, DC5 with K20A2/Z1)
• Honda Civic Type R (EP3, JDM K20A)
• Acura CSX Type-S (Canada)
• K20-swapped applications (Miatas, Minis, etc.)

Critical Installation Notes & Prerequisites: The performance offered by the BC0042-2 camshafts is contingent upon a correctly prepared engine. Installation is not a simple drop-in procedure. Mandatory supporting modifications include: Upgraded valve springs and titanium retainers (such as Brian Crower BC-0240 or equivalent) to control the increased lift and prevent valve float. High-performance timing chain tensioner is strongly recommended. Engine Management: A standalone ECU or advanced reflash tuning (Hondata FlashPro, K-Pro) is ABSOLUTELY REQUIRED to properly adjust fuel maps, ignition timing, and VTEC engagement points. Failure to tune will result in poor performance, drivability issues, and potential engine damage. Professional installation by a qualified technician familiar with K-series valve timing is highly advised.

Technical Specifications & Comparison

The following table details the exact specifications of the BC0042-2 camshaft set, providing a clear, technical comparison to a typical OEM profile. Note that specifications are subject to change; always verify with the manufacturer for the latest data.