Reinforced ARP bolts and nuts for OEM rods PORSCHE 911 3.2 3.3 TURBO 930

The Porsche 930 engines concerned

This kit is for the twelve-valve six-cylinders of the Porsche 911 type 930: the naturally aspirated 3.2-litre (3,164 cm³, 207 to 231 hp), fitted from 1983 to 1989 to the 911 Carrera 3.2, Targa, Cabriolet and Speedster, and the turbocharged 3.3-litre (3,299 cm³, 265 to 330 hp), fitted from 1977 to 1990 to the 911 Turbo 3.3 and 3.3 SC Turbo.

The diameter and reference of the original rod bolt are not published; this ARP kit replaces it on the Porsche 911 3.2-litre and 3.3-litre turbo, and the maker presents it for the 930 and 930/M30 engines.

Reinforced ARP bolts and nuts for connecting rods

Few parts of the bottom end work as hard as the rod bolt: at every revolution, it is what stops the cap from pulling away under the inertia loads of the rod and piston assembly. The original bolt is designed for stock power.

The ARP 204-6005 kit is made of ARP2000. The instruction sheet recommends measuring the bolt stretch, 0.254 to 0.267 mm, and gives a 54.2 Nm torque only when no gauge is available. ARP2000 is an alloy steel developed by ARP and heat treated to 220,000 psi tensile strength; its threads are rolled after heat treatment. Standard engine fasteners commonly fall into classes 10.9 and 12.9, i.e. 150,800 to 176,900 psi minimum strength: ARP2000 sits 24 to 46% above that. In ARP2000, these bolts are rated for 10,250 rpm at most (calculated estimate).

Technical specifications

According to the ARP instruction sheet, the bolts are pressed in and their nuts are tightened by measuring the stretch; the chamfer around the rod bore must clear the radius under the bolt head.

Tightening torque and stretch

For this part, ARP favours tightening to a measured stretch, the key to an exact preload; torque is given only when no gauge is available. The figures in the table assume ARP lubricant.

Source of the torque and stretch figures: ARP 204-6005 instruction sheet, in the revision applicable at publication. The manufacturer's instruction sheet prevails in the event of any difference. Read the ARP 204-6005 instruction sheet

No thread locker is called for by the ARP instruction sheet for this kit: the bolts are fitted with ARP Ultra-Torque grease, on their threads and on the bearing face of the nuts.

The ARP instructions for this kit require the big ends to be checked and resized once the fasteners are fitted: this job belongs to an equipped machine shop.

Measuring bolt stretch

With the stretch gauge, you read directly how much the bolt stretches during tightening: the dial gauge sits on both ends of the fitted bolt, and tightening stops when the stretch reaches the value in the table. Friction no longer comes into play, hence a more consistent preload on a heavily stressed 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

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 a supercharged or track-built 911 six-cylinder, every rod bolt takes a heavy pull on each cycle. If a single one lets go, the engine is destroyed: replacing the bolts in time costs far less than rebuilding the whole bottom end.