The I-Beam Connecting rods for BMW M3 S14 2.3L & 2.5L are constructed from high tensile 4340 steel, designed for high performance and durability. The bushings utilize AMPCO 18 material, providing excellent wear and fatigue resistance, with a radial groove that acts as an oil reservoir. Each rod is shot peened to relieve stress and undergoes multi-stage heat treatment to enhance rigidity. Precision manufacturing ensures tight tolerances for optimal fitment and oil clearances, while controlling bend and twist. Each rod is equipped with ARP 2000 cap fasteners rated at 220,000 psi, with an optional upgrade to ARP L19 material rated at 260,000 psi. The kit includes ARP moly and comprehensive fitting instructions.

Additional Machining Processes

• Dowel sleeves for precise fit and accurate reassembly
• Lipped Cap Relief for enhanced big-end integrity under extreme conditions
• Grooves in Thrust Face for weight reduction

Technical Features of ZRP Connecting Rods

• I-Beam shape for increased rigidity
• Two-piece forging for superior strength
• Shot peening to improve fatigue life
• Magnaflux inspection to ensure material consistency meets high standards
• Double ribbed caps for added support
• Multi-stage heat treatment for maximum strength, dimensional stability, and fatigue life
• CNC machining for superior tolerances, precise to 0.0002″
• Center-to-center maintained under 0.001″ tolerance
• Finite Element Analysis (FEA) for computer-generated stress analysis of connecting rods
• Optimal balancing for weight-matched sets within ± 1 gram