Reinforced ARP main studs for VOLVO B5254 (2000 and later)

The Volvo B5254 engine

This kit is intended for the Volvo B5254, a 20-valve inline five-cylinder of 2,435 cc that the ARP catalogue lists as a 2.5L. It matches the ARP application for engines from the year 2000 onwards.

Originally, Volvo fasteners clamp the main caps and the intermediate section of the bottom end; the kit's studs, in three diameters, take their place.

Reinforced ARP studs for main bearings

The bottom end rests on its main bearings: combustion after combustion, the loads coming from the connecting rods end up on them. Under this stress the main cap tries to move on its parting line, which eventually brinells the mating faces and distorts the bearing bore.

This kit contains 29 ARP2000 studs: 12 in M10 x 1.5 (positions 1 to 12), 12 in M8 x 1.25 (13 to 24) and 5 in M7 (25 to 29), which replace the original fasteners of the main caps and the intermediate section of the B5254. The block is cleaned and its threads are chased if needed with the ARP taps, then the M10 studs are screwed in by hand only. The M8 and M7 studs are fitted using their hexagonal socket. Washers and nuts are coated with ARP Ultra-Torque, which the instructions prefer to engine oil. ARP2000 is an alloy steel developed by ARP and heat treated to 220,000 psi tensile strength. Standard engine fasteners commonly belong to property classes 10.9 and 12.9, i.e. 150,800 to 176,900 psi minimum tensile strength: ARP2000 therefore sits 24 to 46% above that. On this five-cylinder engine, the ARP2000 studs in M10 x 1.5 / M8 x 1.25 / M7 are rated for 1,300 hp at most (calculated estimate).

Technical specifications

Tightening torque

Fitting the studs: screwed into the block by hand, without tightening torque. A Loctite thread locker is an option according to the ARP instructions, for a permanent stud installation.

The M8 and M7 studs are fitted using the hexagonal socket at their end. Tightening follows the manufacturer's sequence: M10 at 41 Nm (30 ft-lb), M8 at 34 Nm (25 ft-lb), M7 at 20 Nm (15 ft-lb), then a second pass on the M10 studs at 88 Nm (65 ft-lb).

Follow the cap tightening sequence recommended by the manufacturer when bringing the nuts up to torque; the kit's instruction sheet details each step.

Stronger fasteners change the clamping force: the size and roundness of the main bearing bores are checked after installation, and the bores are line-honed if necessary, using the final fasteners and lubricant.

Values taken from the ARP 219-5801 instruction sheet in force at the date of publication; the official instruction sheet prevails should any difference appear. Read the ARP 219-5801 instruction sheet

Technical guide

Tightening is done with ARP assembly grease: the torque figures in the table were established with it, not with engine oil.

The ARP brand

Coming from the aerospace industry, Gary Holzapfel founded ARP (Automotive Racing Products) in the early 1970s to put an end to engine failures caused by weak fasteners in motorsport. The company designs and manufactures thousands of part numbers in California, in several material grades depending on the application.

Advantages over the original bolts

Criterion	Original main bolts	Reinforced ARP studs
Tightening	The bolt's rotation loads the block thread	Only the nut turns, the block thread is left unloaded
Repeated refits	The block thread wears with every screwing	The stud stays in place, the block thread is preserved
Locating the caps	The cap has to be held while screwing	The studs guide and hold the cap

When studs become necessary

• B5254 built for the circuit, rally or pure acceleration
• Boost pressure and revs far above stock
• Engine out and the short block completely rebuilt
• Main bearing or intermediate section that no longer holds its clamp load
• Forged crankshaft, rods or pistons fitted at the same time

Vehicle compatibility

Why is it the most cost-effective solution?

A B5254 pushed well beyond stock loads its bearings harder than Volvo planned for. By holding the caps and the intermediate section more securely, this kit protects the crankshaft and the block at a cost far below rebuilding a bottom end.