ARP2000 reinforced crankshaft main studs for Toyota 2AZ-FE

The Toyota engine concerned

The 2AZ-FE is Toyota's naturally aspirated 2.4-litre inline four-cylinder petrol engine (2,362 cm³, 88.5 mm bore, 96 mm stroke), built from 2000 to 2012. It powers the Toyota Camry, RAV4, Previa and Alphard, among others.

Reinforced ARP studs for main bearings

On a crankshaft, the main caps are what hold the shaft against the loads passed on by the connecting rods. If their clamping force drops, the cap shifts slightly on its parting line at every cycle: the mating faces become marked (brinelling), then the bearing bore goes out of round.

This kit replaces the original main cap bolts with ARP2000 studs, with their nuts and washers as the ARP instruction sheet lists them. Each stud is screwed hand-tight into the block and the caps are fitted over them; washers and threads are then lubricated with ARP assembly lubricant and the nuts are torqued in three passes. Preload becomes higher and more consistent, and the block threads are protected.

Material: ARP2000, an alloy steel developed by ARP, rated at 220,000 psi tensile strength, with threads rolled after heat treatment. Against classes 10.9 and 12.9 of standard fasteners, between 150,800 and 176,900 psi minimum, it offers 24 to 46% more strength. On this four-cylinder engine, the ARP2000 studs in M10 x 1.5 are rated for 1,000 hp at most (calculated estimate).

Technical specifications

Tightening torque

No torque is applied to the stud as it goes into the block: it is screwed in by hand. For a permanent installation, the instruction sheet leaves the option of a thread locker of the blue Loctite type on the block end, with the nuts fully tightened before it cures, never on the nuts and never mixed with ARP grease.

The nuts are tightened in the sequence the manufacturer specifies for the main caps; the instruction sheet supplied with the kit describes the full procedure.

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

The torque figures above come from the ARP 203-5401 instruction sheet, revision applicable at publication. The official instruction sheet is authoritative in the event of any difference. Read the ARP 203-5401 instruction sheet

Technical guide

All the torque values on this page assume ARP assembly grease; with engine oil they are no longer correct.

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	ARP studs
Tightening	Bolt screwed straight into the block	Three torque passes, steady build-up
Threads in the block	Loaded by the turning bolt at every tightening	Stud screwed in by hand, no torque
Refitting the caps	Cap held by hand while the bolts go in	Cap guided by the two studs

When studs become necessary

• Power increase from a turbo, supercharger or higher boost
• Stroker crankshaft or higher rev limit
• Complete bottom end strip-down
• Bearing bores or block threads already fatigued
• Intensive motorsport use

Vehicle compatibility

Why is it the most cost-effective solution?

On a tuned 2AZ-FE, particularly a turbo conversion, ARP2000 studs clamp the main caps harder than the original bolts and so limit the risk of bottom-end damage. Their cost is small next to repairing a crankshaft and a block.