Reinforced ARP bolts and nuts for OEM rods PEUGEOT CITROEN LANCIA SAIPA XU9J4 XU10J4

The PSA XU9J4 and XU10J4 engines concerned

This kit is for the sixteen-valve four-cylinders of PSA's XU family: the 1.9-litre XU9J4 (1,905 cm³, 147 to 160 hp), fitted from 1987 to 1993 to the Peugeot 309 GTI 16 and 405 Mi16 and to the sixteen-valve Citroën BX GTi, and the 2.0-litre XU10J4 (1,998 cm³, 126 to 158 hp), fitted to the Peugeot 306, 405, 406, 605 and 806, the Citroën Xantia, XM, ZX, Xsara and Evasion, the Lancia Zeta and the Xantia built by Saipa. The XU9J4Z, XU10J4Z and XU10J4R versions of the same blocks are covered.

The original rod bolts of these blocks, for which neither the reference nor the diameter is published, are replaced by this ARP kit, which the maker intends for the sixteen-valve XU engines of Peugeot and Citroën, the XU9J4 in 1.9 litres and the XU10J4 in 2.0 litres; its instruction sheet names the Peugeot 205 and 306.

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 117-6101 kit is made of 8740 steel. The instruction sheet recommends checking the bolt stretch, 0.178 to 0.19 mm, and gives the 61 Nm torque only when no stretch gauge is available. 8740 is a chrome-moly steel that ARP heat treats to 180,000 psi tensile strength, with threads rolled after heat treatment. As a reference point, standard engine fasteners mostly belong to classes 10.9 and 12.9, i.e. 150,800 to 176,900 psi minimum strength.

Technical specifications

According to the ARP instruction sheet, the bolts are pressed into the rods before the caps are fitted: the top of the rod bore must be chamfered to 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 117-6101 instruction sheet, in the revision applicable at publication. The manufacturer's instruction sheet prevails in the event of any difference. Read the ARP 117-6101 instruction sheet

Assembly is done without thread locker, as the ARP instruction sheet calls for none: ARP Ultra-Torque grease is applied to the threads of each bolt and to the bearing face of its nut.

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

Stretch measurement supplements torque tightening and gives the most accurate preload. It is done with the bolt in place: the gauge, fitted with a dial indicator, bears on both ends of the bolt and shows the stretch achieved, to be brought to the value in the table above. This avoids the variations caused by friction, which matters on a highly 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 sixteen-valve XU that revs high, often built for track or rally use, the rod takes a pull on every cycle that the original bolt was not designed to withstand indefinitely. Replacing the bolts before they let go costs far less than rebuilding an engine.