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4.2L 32v - BNS / BYH / CAUA
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4.2L 32v - BNS / BYH / CAUA
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Set of 8 forged 4340 steel connecting rods for Audi 4.2L 32V BNS-BYH-CAUA.
Introduced by Audi in the mid-2000s, this naturally aspirated 4.2 FSI V8 of 4163 cc (84.5 mm bore, 92.8 mm stroke, 32 valves) powers the RS4 quattro B7 (code BNS, 420 hp, 2005-2008), the first-generation R8 Coupé (code BYH, 420 hp, 2007-2010) and the S5 Coupé (code CAUA, 354 hp, 2007-2012). Direct FSI injection and a 90-degree architecture characterise this high-end unit, which already features a forged crankshaft on its most powerful versions.
Under sustained high-performance use (track days, circuit driving, tuning), extended high-rpm operation and increased cylinder pressure put the factory rods, usually made of sintered metal, at risk of failure. NSB Concept offers a set of 8 forged ZRP connecting rods in 4340 steel to secure the bottom end of these Audi V8 engines for tuning or sustained track use.
Unlike a cast or sintered rod, a forged connecting rod is shaped hot under high pressure: the metal's grain flow follows the shape of the part, which improves fatigue resistance as well as bending and compression strength. This manufacturing process is sought after for bottom ends used in rally, drift, drag racing, circuit racing, hillclimb or time attack, as well as for Stage 2, Stage 3 and beyond builds, whenever forged pistons are fitted, engine speed increases, or boost pressure and displacement are raised.
| Reference | Brand | Profile | Hardware | Pin diameter OEM 20 mm | Small-end width | Big-end diameter OEM 56.8 mm | Big-end width | Center-to-center OEM 154 mm | Weight per rod |
|---|---|---|---|---|---|---|---|---|---|
| R-AUD-012-I | ZRP | I | ARP 2000-3/8"-38mm | 20 | 56.8 | 19.4 | 154 | 507 | |
| R-AUD-012-I-L19 | ZRP | I | ARP L19-3/8"-38mm | 20 | 56.8 | 19.4 | 154 | 507 |
| Rod | Hardware | Torque | Recommended stretch |
|---|---|---|---|
| ZRP (R-AUD-012-I) | ARP 2000 | 61.0 N·m | 0.140 – 0.152 mm |
| ZRP (R-AUD-012-I-L19) | ARP L19 | 67.8 N·m | 0.152 – 0.165 mm |
Manufacturers recommend the stretch method (dial indicator) as the reference: the instructions supplied with the kit always take precedence. The torque values shown correspond to assembly with ARP lubricant.
NSB Concept rods are machined from a chromium-molybdenum 4340 alloy steel, forged and then quenched and tempered. Compared with the sintered metal used in factory rods, this material offers a yield strength about 19% higher, a tensile strength increased by nearly 8%, and fatigue resistance improved by 19 to 37% depending on the load case. It is a proven alloy in aerospace as well as motorsport for its ability to withstand repeated load cycles without weakening.
| Yield strength: about +19% vs sintered metal |
| Tensile strength: about +8% vs sintered metal |
| Fatigue resistance: +19 to +37% vs sintered metal |
For this engine, NSB Concept exclusively offers the I-beam profile, lighter and particularly suited to naturally aspirated or moderately boosted engines seeking a good balance between stiffness, reduced mass and high-rpm reliability.
 | I-beam profile: I-shaped section offering good stiffness for a contained mass, suited to high engine speeds. |
The choice of rod bolt depends on the target power and engine speed. On this listing, the ZRP rods are offered with a 3/8" bolt diameter in two ARP grades:
 | ARP 2000: tensile strength of about 220,000 psi (1,517 MPa), for use up to 200 hp/cylinder in 3/8" and a maximum speed of 8,500 rpm. High-performance standard, with no particular storage constraint, suited to circuit, track day, drift, rally, drag racing and hillclimb. |
 | ARP L19: tensile strength of about 260,000 psi (1,793 MPa), for use up to 250 hp/cylinder in 3/8" and a maximum speed of 10,000 rpm. Designed for engines pushed to the extreme (high boost pressure, sustained high rpm, high cylinder pressure): drag racing, drift, rally and circuit. Sensitive to corrosion and hydrogen embrittlement, it must be stored and fitted oiled. |
| The stretch method (dial indicator) is more precise than plain torque: it directly measures the actual bolt tension, independent of friction. A dedicated ARP stretch gauge lets you check the value during assembly. |
 | ZRP: Greek brand based in Athens, founded by Alex Drakos. The rods are forged from 4340 steel, precision machined and balanced to ±1 g to limit vibration at high rpm. A trusted choice for circuit, drift and rally builds thanks to its robustness and reliability. |
 | 1) Small end 2) Small-end diameter 3) Rod beam 4) Rod bolt 5) Big end 6) Rod nut / bolt 7) Rod cap 8) Big-end diameter 9) Center-to-center |
This set of forged connecting rods is compatible with the following Audi engines:
| Brand | Model (chassis) | Engine code | Power | Years |
|---|---|---|---|---|
| Audi | RS4 quattro Sedan / Avant / Cabriolet (B7) | BNS | 420 hp | 2005–2008 |
| Audi | R8 Coupé (Type 42) | BYH | 420 hp | 2007–2010 |
| Audi | S5 Coupé (8T) | CAUA | 354 hp | 2007–2012 |
Importing forged ZRP connecting rods yourself from Greece involves international shipping costs, uncertain lead times and no French-language technical support if you have doubts about fitment or bolt selection. NSB Concept lists these rods directly, with tracked stock, shipping from France and technical support for choosing the profile, the hardware and checking bolt stretch. The complete kit (rods and ARP hardware) is delivered ready to fit, with no extra steps on your part.
