BC6116 – Mitsubishi/DSM 4G63 2nd Gen/7 Bolt – I-Beam Extreme w/ARP Custom Age 625+ Fasteners – 156mm

In the relentless pursuit of horsepower and reliability, the connecting rod stands as the unsung hero, the critical pivot point between the piston’s explosive force and the crankshaft’s rotational fury. For the legendary Mitsubishi/DSM 4G63 2nd Gen 7-bolt engine, this component becomes the defining limit. The Brian Crower BC6116 I-Beam Extreme Connecting Rod Set is engineered to obliterate that limit. This is not merely an upgrade; it is a foundational re-engineering of the rotating assembly, designed for forced induction builds, high-RPM applications, and engines where factory fatigue points are unacceptable. Manufactured from premium 4340 chromoly steel, utilizing a forged I-beam design for optimal strength-to-weight ratio, and secured with the pinnacle of fastener technology—ARP Custom Age 625+ rod bolts—this set transforms the 4G63’s bottom end into a fortress of rotational integrity.

Engineering the Unbreakable Link: Core Construction & Design

The BC6116 rod begins its life as a premium grade of 4340 chromoly steel, a material celebrated for its exceptional tensile strength and superb fatigue resistance. The manufacturing process is where theory becomes reality. Each rod is precision forged under immense pressure, aligning the grain structure of the metal to follow the contours of the rod’s shape. This forging process creates a part that is inherently stronger and more durable than a machined-from-billet or cast component, as the forged grain flow resists crack propagation. The chosen profile is the classic I-beam, a design revered for its perfect balance of rigidity and weight. The I-beam shape provides massive resistance to column buckling (the tendency of the rod to bend under extreme cylinder pressure) while meticulously machining away unnecessary material to keep rotational mass and inertial stresses in check. Every critical surface, from the beam itself to the pin and crank bores, undergoes CNC machining to exacting tolerances, ensuring perfect balance and a consistent, precise fit within your engine assembly.

The Heart of the Matter: ARP Custom Age 625+ Fastener Technology

Even the world’s most perfectly forged rod is only as strong as its weakest point, which is traditionally the fastener. Brian Crower eliminates this vulnerability by specifying ARP Custom Age 625+ rod bolts as the standard inclusion. This is a game-changer. The 625+ designation refers to a proprietary maraging steel alloy capable of achieving a 260,000 psi tensile strength. Unlike standard hardware or even high-grade ARP 2000 bolts, the 625+ fasteners are virtually immune to the effects of hydrogen embrittlement and offer phenomenal fatigue life. Their “Custom Age” heat-treating process allows them to maintain this extraordinary clamping force and yield strength at elevated temperatures common in high-performance and turbocharged engines. By factory-equipping the BC6116 with these fasteners, the assembly’s ceiling for safe clamping force is raised exponentially, directly translating to an ability to withstand previously unimaginable levels of cylinder pressure and piston acceleration without suffering a catastrophic fastener failure.

Primary Performance & Reliability Benefits

• Extreme Tensile & Fatigue Strength: Forged 4340 chromoly I-beam construction is engineered to withstand the punishing cylinder pressures of high-boost turbocharged and nitrous-assisted applications, offering a massive safety margin over OEM and lesser aftermarket rods.
• Unmatched Fastener Integrity: Inclusion of ARP 625+ rod bolts sets a new standard for included hardware, providing the ultimate in clamp load retention and resistance to stretching or failure under extreme thermal and pressure cycles.
• Optimized Rotational Mass: Precision balancing and weight-matching reduce harmonic vibrations, decrease stress on the crankshaft, and contribute to smoother high-RPM operation and improved engine longevity.
• Precision Fit for Consistent Power: CNC-machined to exacting specifications, these rods ensure perfect bearing crush and alignment, promoting optimal oil film stability and reducing the risk of spun bearings.
• Foundation for Massive Horsepower: This rod set is a cornerstone component for builds targeting 500+ horsepower and beyond, providing the robust, reliable foundation necessary to harness and convert that power reliably.

Technical Specifications & Dimensional Data

Precision is paramount. The BC6116 is engineered to the stock 4G63 7-bolt connecting rod length of 156mm (6.102 inches), center-to-center. This maintains correct piston deck height and compression ratio when used with standard compression height pistons. The small end is precision honed for a specific press-fit or floating piston pin application (confirm based on your piston choice), while the big end is sized and finished for perfect bearing installation. Each rod in the set is weight-matched to an exceptionally tight tolerance, a critical step for a balanced rotating assembly that minimizes destructive harmonics. For a deeper technical dive into 4G63 bottom-end assembly theory and best practices, consider this resource on DSM Forums: 4G63 Connecting Rod and Bearing Clearance Tech.

Vehicle & Engine Fitment

The BC6116 is specifically engineered for the Mitsubishi 4G63 engine in its 2nd Generation, 7-bolt crankshaft configuration. This critical distinction is essential, as earlier 6-bolt engines and the very different 4G63 found in the 2006+ Evolution IX (and later) have different rod specifications. This set is a direct replacement for the factory connecting rods in the following applications:

Primary Applications:

Mitsubishi Eclipse GS-T / GSX (1992.5-1999): All turbocharged models within these model years utilizing the 7-bolt engine block. This is the core DSM application.
Mitsubishi Eclipse Spyder GS-T (1997-1999): The turbocharged convertible variant.
Eagle Talon TSi / Plymouth Laser RS Turbo (1992.5-1994): The DSM triplets. Confirm your engine is the 7-bolt version.
Mitsubishi Galant VR-4 (1992-1993): The legendary all-wheel-drive sedan.
Non-Turbo 4G63 7-Bolt Engines: While less common for performance builds, this rod set will physically fit any 7-bolt 4G63 (e.g., 1994-1999 Eclipse RS/GS). However, its true potential is realized in forced-induction or high-RPM builds.

Critical Note: Always verify your engine’s internal configuration. The 7-bolt crankshaft has a specific rod journal size. These rods are not compatible with 1st Generation (1990-1992.5) 4G63 6-bolt engines or the 2006+ Evolution IX/X 4B11T engine. Professional installation, including precise measurement of bearing clearances (both rod and main), is absolutely mandatory.

Installation Considerations & Final Assessment

Installing the BC6116 rods is a procedure that demands precision machining and measurement. They are a “machined-ready” component, not a “bolt-in” part. The big end bore must be measured, and the appropriate bearing shell selected to achieve the manufacturer-specified oil clearance—typically between 0.0018″ and 0.0022″ for a performance street/track engine. The small end must be checked for proper piston pin fit, whether for a pressed or floating pin configuration. A full rotating assembly balance is highly recommended when installing these rods with new pistons and pins. The inclusion of the ARP 625+ fasteners requires the use of a stretch gauge for proper installation, as the torque-plus-angle method is not sufficiently accurate for bolts of this caliber. Following ARP’s specific installation lubricant and stretch specification is non-negotiable for achieving the designed clamp load.

In final assessment, the Brian Crower BC6116 I-Beam Extreme Rod Set with ARP 625+ fasteners represents the definitive solution for builders who refuse to compromise on bottom-end integrity. It bridges the gap between high-end street performance and all-out competition duty. By addressing the two most critical aspects—forged 4340 I-beam construction and ultra-premium fasteners—in one complete package, it delivers a level of security and performance headroom that allows you to push the 4G63 platform to its modern limits with confidence. This is the rod you install when the question isn’t “if” you’ll make power, but “how much” the engine’s architecture can truly hold.