BC0118 – Mitsubishi 4G64 Block/4G63 Head Stroker Kit – 102mm Stroke/ProH625+ Rods (H Beam)

The Architect of Displacement: Engineering the Ultimate 4G6x Stroker Foundation

For the dedicated builder whose pursuit of power is governed by precision, not conjecture, the Brian Crower BC0118 Stroker Kit represents the definitive blueprint for transforming the venerable Mitsubishi 4-cylinder platform. This isn’t merely a collection of parts; it’s a cohesive engineering system designed to unlock the latent potential of the 4G64 block and 4G63 cylinder head combination. Targeting a colossal 2.5-liter final displacement via a calculated 102mm stroke, this kit provides the architectural core for builds demanding relentless torque, expansive power bands, and absolute durability under extreme boost or high-RPM stress. Every component, from the 4340 billet steel crankshaft to the legendary ProH625+ H-beam connecting rods, is machined to exacting tolerances, ensuring that when you’re orchestrating the symphony of forced induction or aggressive naturally aspirated tuning, the bottom end is the last of your concerns. This is the foundation upon which 500, 700, even 1000+ horsepower legends are forged.

Centrepiece of Force: The 4340 Billet Crankshaft & 102mm Stroke

The heart of any stroker assembly is the crankshaft, and the BC0118 delivers a masterpiece of rotational mass engineering. Forged from premium 4340 chromoly billet steel, this crank undergoes a rigorous CNC machining and precision balancing process, resulting in a component with superior grain structure and fatigue resistance compared to cast or even forged OEM units. The critical 102mm stroke is not an arbitrary increase; it’s a calculated enhancement that significantly increases engine displacement and, consequently, torque production across the entire rev range. This extended stroke, when paired with the correct piston, optimizes the rod-to-stroke ratio, mitigating excessive cylinder wall loading and ensuring efficient combustion dynamics. Each journal is micro-polished to a mirror finish, drastically reducing friction and enhancing oil film stability, which is paramount for maintaining bearing integrity under the tremendous loads generated by high-boost applications. This crankshaft is the immutable anchor of your powerplant, designed to transfer combustion forces with unwavering rigidity.

Structural Integrity: ProH625+ H-Beam Connecting Rods

Linking the aggressive motion of the stroker crankshaft to the piston is a task that demands a rod of exceptional strength and resilience. Brian Crower’s ProH625+ H-beam rods are the industry benchmark for a reason. Machined from 4340 chromoly steel billet, their distinctive H-beam design provides an optimal balance of minimal weight and maximal strength, offering incredible resistance to buckling and stretching under load. The “+” designation indicates upgraded, high-lube wrist pin bushings for improved piston pin oiling and durability, a critical detail in high-horsepower environments. These rods are weight-matched and shot-peened, a process that induces compressive surface stresses to dramatically improve fatigue life. Paired with the 102mm stroke crank, they help establish a robust and reliable rotating assembly that can confidently handle the explosive cylinder pressures of modern turbocharging strategies, making them a non-negotiable component for any serious performance or competition build.

Complete System Synergy: Kit Components & Assembly Philosophy

The BC0118 kit’s supremacy lies in its completeness and component synergy. It eliminates the guesswork of part compatibility, supplying a fully balanced rotating assembly ready for meticulous installation.

• Fully Balanced Rotating Assembly: Every component – crankshaft, rods, pistons (typically included in full kits), and harmonic damper – is balanced as a unit. This is critical for smooth operation, especially at the elevated RPM limits a built engine can achieve, reducing destructive harmonics and bearing wear.
• Precision Engineered Pistons: While piston selection may vary, kits are typically configured with forged aluminum pistons featuring valve reliefs cut specifically for the 4G63 head’s aggressive cam profiles and stroker clearance requirements, ensuring perfect compatibility and optimal compression ratio.
• High-Grade Fasteners: The inclusion of ARP or equivalent premium rod bolts is standard. These are the critical links holding the rod caps; their tensile strength and clamping force are essential for preventing catastrophic rod cap separation under detonation or over-rev.
• Displacement & Torque Revolution: Transitioning from a standard 2.0L or 2.4L to a 2.5L stroker fundamentally changes the engine’s character. The increased displacement provides a massive gain in low-end and mid-range torque, improving throttle response and reducing turbo lag, effectively making the powerband broader and more usable.
• Blueprint for Massive Power: This assembly is designed not as a final goal, but as the essential foundation. It supports the horsepower ceilings required for today’s performance standards, reliably containing the cylinder pressures needed to make 600+ horsepower a routine achievement.

Technical Specifications & Component Data

Vehicle Fitment & Application Guidelines

The BC0118 kit is engineered explicitly for the renowned “4G64 bottom end / 4G63 top end” hybrid stroker configuration. This combination leverages the taller deck height of the 4G64 block (found in many USDM vehicles) to accommodate the longer stroke, while utilizing the superior airflow and performance aftermarket of the 4G63 cylinder head. Proper fitment requires meticulous attention to ancillary components and clearancing.

Direct Block Compatibility:
Mitsubishi 4G64 (2.4L) engine blocks from:
1994-1998 Mitsubishi Eclipse RS/GS (Non-Turbo)
1994-1998 Eagle Talon (Non-Turbo)
1994-2003 Mitsubishi Galant (4-cylinder models)
2002-2006 Mitsubishi Lancer/Outlander (4G69 variant blocks may require verification)

Cylinder Head & Drivetrain Pairing:
The kit is designed to be used with a Mitsubishi 4G63 cylinder head, sourced from:
1990-1999 Mitsubishi Eclipse/Talon/Laser Turbo (6-bolt or 7-bolt)
1992-2006 Mitsubishi Lancer Evolution I-IX
This requires use of the 4G63 head’s corresponding intake/exhaust manifolds, timing components, and front case. The assembly will mate to both manual and automatic transmissions used with these engines. Critical Note: Installation of a stroker kit of this magnitude is a professional engine rebuild procedure. It mandates thorough block machining (boring, honing, decking), precise piston-to-valve and rod-to-block clearancing checks, and the use of complementary high-performance valvetrain, oiling, and engine management systems. For a deeper technical dive into the theory and benefits of stroker engine builds, consider reading this resource on engine building fundamentals at Engine Builder Magazine.