Reinforced ARP cylinder head studs Honda Acura C30A C30A3 C30A4 C32B1 C32B2

The engines concerned

The C30A, C30A3 and C30A4 (2,977 cc, bore 90 mm, stroke 78 mm) and the C32B1 and C32B2 (3,179 cc) are the 3.0 and 3.2-litre petrol V6 engines of the Honda and Acura NSX, naturally aspirated, with twenty-four-valve VTEC, built from 1990 to 2005. ARP offers a single ARP2000 stud kit for them, the 208-4309, with 12-point nuts.

These V6 engines are originally fitted with head bolts, which these ARP studs replace.

Reinforced ARP cylinder head studs

The job of the head fasteners is to keep the cylinder head locked to the block despite the pressure inside the combustion chambers. They keep the gasket compressed; as soon as their clamping force drops, leaks appear between head and block.

For these V6 engines the ARP catalogue lists the 208-4309 kit, in ARP2000, with 12-point nuts, designed for both cylinder heads of the NSX. The ARP2000 range relies on an alloy steel developed by ARP: after heat treatment it reaches 220,000 psi tensile strength, and the threads are rolled afterwards. As standard bolts generally belong to classes 10.9 and 12.9, i.e. 150,800 to 176,900 psi minimum, ARP2000 exceeds them by 24 to 46 %. As an estimate, this ARP2000 kit, heat-treated to 220,000 psi tensile strength, suits tuned 3.0 and 3.2-litre V6 engines.

Technical specifications

Tightening torque

Technical guide

When assembling, the threads and the nut bearing faces receive ARP Ultra-Torque lubricant rather than engine oil. The torque and tightening sequence are to be read in the instruction sheet supplied with the kit.

The ARP brand

Gary Holzapfel, a former aerospace engineer, created ARP (Automotive Racing Products) in the early 1970s to tackle engine failures caused by insufficiently strong fasteners in racing. Today the brand develops and manufactures thousands of parts in California, available in several material grades as needed.

Advantages over the original bolts

Criterion	Original head bolts	Reinforced ARP studs
Engine block threads	Stressed at every tightening	Preserved: the stud stays in place

When studs become necessary

The original fasteners are sized for the engine as it leaves the factory. They need to be reinforced when:

• Tuned C30A or C32B V6, naturally aspirated or boosted: output beyond stock
• The compression ratio rises as the build progresses
• The original gasket is replaced by a reinforced MLS gasket, which requires a high and uniform preload
• The engine has already suffered a lifted head or a gasket leak
• Competition use imposes severe heat cycles and regular head removals

Vehicle compatibility

Why is it the most cost-effective solution?

On a tuned C30A or C32B V6, the original head fasteners cap the pressure the gasket can hold. ARP2000 studs with 12-point nuts push that cap back, for an outlay that bears no relation to reopening an NSX engine after a blown head gasket.