ZRP Forged 4340 I-Beam Conrods for BMW N55/N55B30 3.0L Straight-6 – 144.35mm Length, 22mm Wrist/Gudgeon Pin, ARP 2000 Bolts (Set of 6) | Performance Connecting Rod Upgrade | Fits 135i 235i 335i 435i M2

ZRP Conrods for BMW N55 3‑litre Straight‑Six – Part No. R-BMW-019-I

Build your N55 bottom end with confidence. This six‑piece ZRP rod set is crafted from high tensile 4340 steel and finished to exacting motorsport tolerances for dependable strength in hard‑driven, tuned applications. We have installed these in‑house at MJ Modifications and our customers love the fit, finish and durability under serious power.

Perfect for remapped and big‑power N55 builds that see road, track day or drag use, these performance con rods bring the reliability you need when raising boost, running hybrid or single turbo setups, or pushing higher RPM. Weight matched, crack‑checked and supplied with premium fasteners, they are the ideal foundation for an N55 engine refresh or full forged build.

Key benefits

• High strength 4340 steel I beam construction for superb rigidity under load
• Two‑piece forging, shot peen treatment and multi‑stage heat treatment for fatigue resistance
• AMPCO 18 bush with radial oiling groove for excellent small‑end wear characteristics and lubrication
• Precision CNC machining with tolerances as tight as 0.0002 inch and centre‑to‑centre control within 0.001 inch
• Magnaflux inspected and FEA validated design for material integrity and reliability
• Weight matched to within ±1 g for smooth running and balanced rotating assembly
• Double‑ribbed caps with dowel sleeves for secure cap alignment and repeatable torque accuracy
• Includes ARP 2000 3/8 inch rod bolts with ARP moly lube, with optional ARP L19 upgrade available

Machining highlights

• Straight‑cut small end for use with aftermarket pistons only
• Lipped cap relief for added big‑end stability under extreme cylinder pressures
• Thrust face light‑weighting grooves without compromising strength

Dimensions and details

• Engine family: BMW N55 3.0 litre
• Rod type: I beam forged steel
• Centre‑to‑centre length: 144.35 mm
• Gudgeon pin diameter: 22.00 mm
• Housing bore: 53.635 mm
• Big‑end width: 20.88 mm
• Typical rod weight: 487 g
• Bolt size: 3/8 inch
• Fasteners: ARP 2000 included, ARP L19 optional
• Quantity: set of 6
• Note: non‑tapered pin end

Compatibility

For BMW N55 petrol engines. The straight‑cut small end requires the use of compatible aftermarket pistons.

What’s in the box

• 6 x ZRP forged steel con rods
• ARP 2000 rod bolts with ARP moly lubricant
• Fitting guidance

Fitting and support

Professional installation is strongly recommended. For installation, machining advice or a full engine build, book with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Part number

R-BMW-019-I

Search terms to help you find this item

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