Reinforced ARP bolts and nuts for OEM rods HONDA ACURA C32B C32B1 C32B2

The Honda C32B engine concerned

The C32B is the 3.2-litre naturally aspirated V6 (3,179 cc, 24-valve VTEC) of the first-generation Honda and Acura NSX built from 1996 to 2005; the NGK catalogue separates it into C32B1 (294 hp) and C32B2 (280 hp).

This kit replaces the original rod bolt of that V6: ARP describes it as a set of bolts to be pressed into the connecting rods, supplied with nuts, for the Acura 3.2L (C32B) V6 NSX.

Reinforced ARP bolts and nuts 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.

Made of ARP2000, this kit goes on in two stages: the bolts are pressed into the rods first, then the nuts are tightened as the ARP instruction sheet directs, preferably by stretch, or to 35.3 Nm 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%. The engine speed allowed by the ARP2000 bolts goes up to 9,500 rpm (calculated estimate).

Technical specifications

Before the bolts are pressed in, the ARP instruction sheet asks you to check that the top of the rod bolt hole has an adequate chamfer, to clear 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 208-6005 instruction sheet applicable at the date of publication; it is authoritative in the event of any difference. Read the ARP 208-6005 instruction sheet

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

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

All the torque and stretch values on this page assume ARP assembly grease on the bolt threads and on the bearing face of the nuts; engine oil does not replace it.

The ARP brand

Founded in the early 1970s by Gary Holzapfel, who came from the aerospace sector, ARP (Automotive Racing Products) was born to put an end to fastener-related engine failures in racing. Its thousands of part numbers, designed and manufactured in California for the cylinder head, the main bearings and the connecting rods, come in several materials depending on the application and are recognised for the consistency of their manufacture.

Vehicle compatibility

Why is it the most cost-effective solution?

On a tuned C32B V6 revved hard, each rod bolt is pulled on at every cycle. Should a single one fail, the rod, the piston and the block go with it: an ARP2000 kit costs far less than rebuilding the whole engine.