Reinforced ARP bolts for OEM rods AUDI VW V6 APB BEL AFC ACK AHA ATQ

The Audi 2.7 twin-turbo and 2.8 V6 engines concerned

This kit covers two Audi V6 engines: the twin-turbo 2.7-litre of 254 to 265 hp (APB, BEL, 2,671 cm³), found in the S4 B5 and B6, the A6 C5 2.7 and the Allroad, and the naturally aspirated 2.8-litre of 174 to 193 hp (AFC, ACK, AHA, ATQ, 2,771 cm³), fitted to the Audi 80, Cabriolet, A4, A6 and A8 as well as to the Volkswagen Passat B5 and B5.5.

This ARP kit takes the place of the original rod bolt of these two V6 engines, a bolt whose reference is not published.

Reinforced ARP bolts for connecting rods

At every engine revolution, the rod and piston assembly pulls on the rod cap, and only its bolts hold it against these inertia loads. The original ones are intended for stock power and for a single installation.

For this ARP2000 kit, the instruction sheet favours tightening by stretch, read with a dial gauge, and gives the 40.7 Nm torque only when no gauge is available. Material: ARP2000, an alloy steel developed by ARP, heat treated to 220,000 psi tensile strength, with threads rolled after heat treatment. Against classes 10.9 and 12.9 of original fasteners, between 150,800 and 176,900 psi minimum, the margin is 24 to 46%.

Technical specifications

According to the ARP instruction sheet, these bolts are fitted without a washer; the rod cap bolt hole needs a chamfer wide enough to house the radius under the head.

Tightening torque and stretch

ARP recommends tightening to a measured stretch, which gives a more accurate preload than torque alone, given as a fallback. Torque and stretch figures assume ARP lubricant.

The values above come from the ARP 204-6201 instruction sheet applicable at the date of publication; it is authoritative in the event of any difference. Read the ARP 204-6201 instruction sheet

The ARP instruction sheet does not require a thread locker for this kit; only ARP Ultra-Torque grease is applied, on the threads as well as under the bolt head.

According to the ARP instructions, the big ends must be checked and resized with the fasteners in place; plan a visit to a machine shop.

Measuring bolt stretch

Tightening to stretch means setting the preload on how much the bolt actually stretches, rather than on a torque affected by friction. With the bolt fitted, the dial gauge is placed on both its ends and the bolt is tightened until the stretch given in the table is read. It is the safest method on a highly tuned engine.

Technical guide

Torque and stretch figures are only valid with ARP assembly grease, applied to the threads and under the head.

The ARP brand

An engineer with an aerospace background, Gary Holzapfel launched ARP (Automotive Racing Products) in the early 1970s with one goal: to eliminate engine failures caused by weak fasteners in racing. ARP designs and manufactures thousands of part numbers in California, cylinder head, main and rod bolts, in several materials depending on the use, and has become known for the consistency of its manufacturing.

Vehicle compatibility

Why is it the most cost-effective solution?

On an Audi V6 pushed hard or boosted, each rod bolt takes an extra tensile load on every turn, and the failure of a single one wrecks the rod, the piston and the block. A set of ARP2000 bolts removes that risk for a fraction of the cost of an engine to rebuild.