BMW 3.0L N55 & S55 I-Beam Connecting Rods

Our I-Beam Connecting Rods for BMW 3.0L N55 & S55 engines are crafted from 4340 high tensile steel, offering a specially optimized shape for high performance and extreme durability. These rods feature a "straight cut" pin end, designed for use with aftermarket pistons, enhancing durability.

The bushings are constructed from AMPCO 18 material, providing excellent resistance to wear and fatigue, and include a radial groove that acts as an oil reservoir. The rods undergo shot peening to relieve material stress and multi-stage heat treatment to increase rigidity. Tight production tolerances ensure perfect fitment and optimized oil clearances, with controlled 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 full fitting instructions.

Additional Machining Processes

• "Straight Cut" Pin End - Suitable for aftermarket pistons
• Dowel sleeves for perfect fit and accurate re-assembling
• Lipped Cap Relief for improved big-end integrity at extreme applications
• Grooves in Thrust Face for weight reduction

Technical Features of ZRP Connecting Rods

• I-Beam Shape for extra rigidity
• Two-Piece forging for great strength
• Shot Peening for improved fatigue life
• Magnaflux Inspection ensures material consistency meets high-quality 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 .001" tolerance
• Finite Element Analysis (FEA) for stress analysis of con rods
• Optimal balancing for weight matched sets of ± 1 gram

These rods support a horsepower range of 175 HP per cylinder with ARP 2000 fasteners and 200 HP+ with ARP L19 fasteners.