Reinforced ARP cylinder head studs Honda D16Y8

The engines concerned

This kit fits the 16-valve inline four-cylinder 1.6-litre Honda D16Y8 engine, fitted notably to the Civic VI (EJ8) and the CR-X del Sol Si (EH6).

As standard, the cylinder head is held by ten Honda head bolts (reference 90005-PM3-003, M11 thread), tightened in three stages to 20, 49 then 67 Nm, with a final pass of bolts 1 and 2 at 67 Nm again. These bolts are screwed into the block thread at every fitting.

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 engines ARP offers kit 208-4305: 8740 studs of 10 mm and 12-point nuts. The instruction sheet asks for the block threads to be cleaned first, the studs screwed in by hand, the head fitted, then the threads, nuts and washers lubricated with the supplied ARP Ultra-Torque lubricant before tightening in three equal passes, in the manufacturer's order. 8740 is a chrome-molybdenum steel, rated by ARP at 200,000 psi tensile strength. As a reference point, an engine's standard fasteners mostly belong to property classes 10.9 and 12.9, with a minimum tensile strength between 150,800 and 176,900 psi. In 10 mm, the 8740 studs hold up to 500 hp on this four-cylinder engine (calculated estimate).

Technical specifications

Tightening torque

The studs are screwed into the block by hand, without torque. Their instruction sheet allows thread locker if they are to be fixed permanently, on the sole condition that tightening is finished before it sets.

If needed, the block threads can be chased with the ARP thread cleaning tool, as the instruction sheet describes.

Where the studs open into the water jacket, the sheet calls for ARP thread sealer on the block threads.

Final tightening is done in three successive stages, following the manufacturer's tightening sequence; these torque figures only hold with ARP assembly lubricant on the threads and under the nuts.

The instruction sheet also calls for ARP lubricant on the washers.

The torque figures above come from ARP instruction sheet 208-4305, revision applicable on the day the page went online. The official instruction sheet prevails in case of difference and describes the complete procedure, tightening sequence included. Read the ARP 208-4305 instruction sheet

Technical guide

The stated tightening torques only make sense with ARP assembly grease, applied to the threads and under the nuts.

The ARP brand

ARP (Automotive Racing Products) was born in the early 1970s from the initiative of Gary Holzapfel, an engineer from the aerospace industry, determined to eliminate engine failures caused by weak fasteners in motorsport. The company designs and manufactures thousands of parts in California, in several material grades suited to each use.

Advantages over the original bolts

Criterion	Original head bolts	Reinforced ARP studs
Tightening method	20, 49 then 67 Nm	Three equal torque passes
Block thread	Works at every fitting	Preserved: studs screwed in by hand

When studs become necessary

On an engine left standard, the original fasteners do their job. Switching to reinforced fasteners becomes worthwhile as soon as:

• Power exceeds stock output, in a strongly tuned naturally aspirated or a boosted build
• The compression ratio is increased
• A reinforced MLS gasket is fitted, with its need for a high and even preload
• The head has already lifted or the gasket has already failed
• The engine is used in competition, with intense heat cycles and repeated teardowns

Vehicle compatibility

OEM reference: 90005-PM3-003

Why is it the most cost-effective solution?

On the D16Y8, the original fasteners are designed for stock power and become the weak link as soon as the build is pushed harder. Replacing the bolts with a kit of ARP 8740 studs costs far less than redoing a cylinder head, gasket and labour included.

Consider a reinforced head gasket

To get the most out of reinforced fasteners, pair them with a head gasket that withstands the same pressure. Here is the gasket we offer for this engine: