BC0228 – Nissan VQ35HR Stroker Kit – 86.4mm Stroke/ProH2K Rods – Balanced

Unlocking the True Potential of the VQ35HR: The BC0228 4.07L Stroker Kit

The Nissan VQ35HR engine represents one of the most robust and tunable inline-six architectures ever produced. While renowned for its smoothness and high-revving nature, its factory displacement ultimately limits its torque output and ultimate power ceiling. The BC0228 Nissan VQ35HR Stroker Kit from Brian Crower is not merely an upgrade; it is a fundamental re-engineering of the platform. This comprehensive, balanced assembly transforms the 3.5L VQ35HR into a 4.07L displacement monster, providing the foundational hardware for builds targeting 500+ reliable wheel horsepower and beyond. Engineered for the serious builder, this kit combines a massive 86.4mm stroke 4340 billet crankshaft with proprietary ProH2K connecting rods and high-compression forged pistons to deliver unmatched low-end torque, extended high-RPM capability, and bulletproof durability. This is the definitive solution for 350Z, 370Z, and G35/G37 enthusiasts demanding maximum naturally aspirated thrust or preparing for forced induction dominance.

Precision Engineering for a 4.07L Displacement Increase

The core of the BC0228 kit’s transformative power lies in its meticulous component selection and design. The increase from the factory 3.5L (3498cc) to 4.07L (4074cc) is achieved through a significant stroke lengthening, moving from the stock dimension to a commanding 86.4mm (3.402 in). This is accomplished via a custom-manufactured 4340 chromoly billet steel crankshaft. Unlike forged or cast units, a billet crank is machined from a single, homogenous block of premium alloy steel, ensuring superior grain structure consistency and ultimate strength with no potential for internal forging flaws. This process allows for precise optimization of counterweight design and journal profiles to handle the immense inertial and combustion forces of a stroked, high-output application.

To pair with this aggressive stroke, BC includes its legendary ProH2K 4340 chromoly connecting rods. The “H2K” designation signifies a rating capable of withstanding 2,000 horsepower, a testament to their overbuilt nature. These rods feature a high-strength 4340 alloy construction, ARP 2000 cap screws as standard, and are Magnaflux inspected for structural integrity. The included forged aluminum pistons are designed with this specific rod and stroke combination in mind, featuring valve reliefs cut for high-lift camshafts and utilizing a premium tool steel wrist pin. The piston rings are quality ductile iron/moly top rings with napier second rings for optimal sealing and oil control, a critical factor in maintaining cylinder pressure and preventing blow-by in high-stress environments. For further technical reading on VQ platform development, a resource like this Engine Labs article on building a better VQ provides excellent foundational knowledge.

Benefits of the BC0228 Stroker Kit Assembly

• Substantial Displacement Gain: Elevates engine capacity from 3.5L to 4.07L, providing an immediate and significant increase in torque and horsepower across the entire RPM band.
• Unmatched Bottom-End Strength: The combination of a 4340 billet crankshaft and ProH2K 4340 connecting rods creates a rotating assembly capable of supporting well over 1,000 horsepower, future-proofing your build.
• Optimized for High RPM: Despite the increased stroke, the kit is fully balanced (optional, but highly recommended) and utilizes lightweight forged components to maintain and even improve high-RPM stability over stock.
• Improved Thermal and Mechanical Efficiency: Forged pistons dissipate heat more effectively and resist detonation, while the precision-machined components reduce parasitic friction losses.
• Direct Bolt-In Compatibility: Engineered as a complete package for the VQ35HR, this kit requires no block machining for the crank (main bearing journals are stock size) and fits within the stock cylinder block, simplifying the build process.
• Foundation for Any Power Goal: Whether the target is a high-compression, high-RPM naturally aspirated beast, a twin-turbo street weapon, or a Procharger-equipped drag car, this rotating assembly provides the necessary core strength.

Complete Harmonic Balancing & Kit Inclusions

An often-overlooked but critical aspect of any stroker kit, especially one with such a significant stroke increase, is harmonic balancing. An unbalanced rotating assembly is a primary cause of premature main bearing failure, excessive vibration, and ultimately, catastrophic engine failure. The BC0228 kit is offered unbalanced, requiring a professional engine builder to balance the entire assembly—crankshaft, rods, pistons, pins, and rings—as a unit. This process ensures that the inertial forces of the reciprocating and rotating masses are neutralized, allowing the engine to operate smoothly at high RPM. Brian Crower strongly recommends, and most seasoned builders insist upon, this crucial service for longevity and performance.

The kit is comprehensive, leaving no critical component to chance. The package includes the 86.4mm stroke 4340 billet crankshaft, a set of ProH2K connecting rods with ARP 2000 bolts, a matched set of forged aluminum pistons with tool steel pins, and a complete piston ring set. Also included are Clevite 77 tri-metal main and rod bearings, renowned for their embeddability and fatigue resistance under extreme loads. This all-in-one approach guarantees component harmony and simplifies procurement, ensuring every part is designed to work in concert with the others.

Vehicle Fitment: Application Specificity

The BC0228 kit is specifically engineered for the Nissan VQ35HR engine code. It is not compatible with the earlier VQ35DE Rev-Up or standard DE. Correct identification of your engine is paramount. This kit is a direct-fit for the following vehicles:

• Nissan 350Z (Z33): 2007-2008 model years (HR engine only).
• Nissan 370Z (Z34): 2009-2020 model years with the VQ37VHR engine. Note: The VQ37VHR utilizes the same block architecture as the VQ35HR, making this kit a direct fit and a foundational part of a “37HR” hybrid build.
• Infiniti G35 (V36): 2007-2008 model years (Sedan & Coupe, HR engine only).
• Infiniti G37 (V36): 2009-2013 model years (Sedan, Coupe, Convertible).
• Infiniti Q50 / Q60: 2014-2015 model years with the 3.7L VQ37VHR engine.

Technical Specifications & Build Notes

Critical Build Notes: Installation of this kit must be performed by a qualified engine machinist and builder. Essential steps include measuring and potentially honing the cylinder block to achieve the correct piston-to-wall clearance, performing a complete balancing service on the entire rotating assembly, and verifying all clearances (main, rod, thrust) during assembly. The use of ARP main studs and a high-volume oil pump is strongly recommended to complement this high-performance rotating assembly. The BC0228 Stroker Kit provides the ultimate foundation; proper installation and supporting modifications are what unlock its full, devastating potential.