Reinforced ARP main studs and bolts for MITSUBISHI 4B11T

The Mitsubishi 4B11T engine

ARP lists these kits for Mitsubishi's 2.0-litre 4B11 turbo: an inline four-cylinder with double overhead camshafts and sixteen valves, built from 2007 to 2016 in its 4B11T form. According to the NGK catalogue, it powers the Lancer Evolution X (280 to 446 hp depending on version) as well as the Lancer Ralliart and Lancer Sportback Ralliart (241 to 250 hp).

Originally, the main caps are held by Mitsubishi bolts in two diameters, M10 and M8; the studs or bolts in these kits replace them, in the same two diameters.

Reinforced ARP bolts and 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.

Two references share this page, both in ARP2000 with two diameters, M10 x 1.25 and M8 x 1.25: the 207-5403 stud kit and the 207-5201 bolt kit. The studs go in by hand only, then the caps are fitted and the nuts tightened; the bolts are tightened straight into the block. The ARP lubricant goes on the threads and nuts, or on the head and threads of the bolts. Tightening is done in three equal steps in the manufacturer's order: M10 at 95 Nm (70 ft-lb), that is 32, 63 then 95 Nm; M8 at 43 Nm (32 ft-lb), that is 14, 29 then 43 Nm. Material: ARP2000, an alloy steel developed by ARP, rated at 220,000 psi tensile strength. 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. These ARP2000 studs in M10 x 1.25 and M8 x 1.25 take up to 1,100 hp on this four-cylinder engine (calculated estimate). On this four-cylinder engine, the ARP2000 bolts in M10 x 1.25 and M8 x 1.25 are rated for 1,100 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 ARP instruction sheet allows a Loctite thread locker, provided the tightening is completed before the product cures.

The bolts pass through the cap and are tightened straight into the block, to torque and in stages, with threads and underside of the head lubricated with ARP grease.

The instructions for the 207-5201 bolt kit do not mention a thread locker, so none is recommended for these bolts.

The nuts and bolts 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 207-5403 and 207-5201 instruction sheets, revisions applicable at publication. The official instruction sheets are authoritative in the event of any difference. Read the ARP 207-5403 instruction sheet ; Read the ARP 207-5201 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.

When to upgrade the main bearing fasteners

• 4B11T with output well above stock
• Lancer Evolution X built for the track, rally or drag racing
• Bottom end opened to take forged parts
• Main bearing housings machined with reinforced fasteners
• Engine used repeatedly at high revs

Vehicle compatibility

Why is it the most cost-effective solution?

An Evo X pushed beyond its stock output asks more of the crankshaft main bearings. ARP2000 studs or bolts on the caps cost little compared with a block and a crankshaft to replace.

Consider the crankshaft main bearings

When the bottom end is open, the bearings are replaced too. Here are the tri-metal crankshaft main bearings designed for these engines: