Reinforced ARP cylinder head studs Nissan CA16DE CA16DET CA18DE CA18DET

The engines concerned

The CA16DE, CA16DET, CA18DE and CA18DET are 1.6 and 1.8-litre 16-valve Nissan four-cylinder engines (1,598 and 1,809 cc in the NGK catalogue), the DET versions being turbocharged. The CA18DE powers the naturally aspirated 180SX, 200SX, Sunny and Bluebird among others, the CA18DET the turbo 180SX and 200SX as well as the Auster Xtt, and the CA16DE the EXA Targa and the Pulsar NX. ARP lists all four codes for each of its two kits.

As built, the CA18DET cylinder head is secured by head bolts, OEM part number 11056-D4200, with their washers 11058-16A01.

Reinforced ARP cylinder head studs

Every combustion cycle pushes the cylinder head upwards. The head fasteners resist it by keeping a constant clamping pressure on the gasket; if that pressure drops, the seal is no longer guaranteed.

Two ARP kits in 8740 fit these engines: studs 202-4302 and 202-4702, both of 7/16 in diameter, the second being an undercut kit according to the 2026 ARP list. The sheets do not give the pitch. They have the studs screwed in by hand only, the head fitted, then threads, nuts and washers lubricated with ARP Ultra-Torque before tightening to torque in three equal passes. 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 7/16 in, the 8740 studs hold up to 600 hp on this four-cylinder engine (calculated estimate).

Technical specifications

Tightening torque

Studs 202-4302 and 202-4702: 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.

All block threads are cleaned before fitting and, if necessary, run through again with the ARP Thread Chaser.

When a stud ends in the water jacket, its block-side threads are coated with ARP thread sealer, applied before the studs go in.

Tightening to torque is done in three steps, in the order set by the engine manufacturer, with ARP lubricant applied to the threads and under the nuts, a condition for the table values to apply.

According to the instruction sheet, ARP lubricant is also applied to the washers, as on the threads.

The torque figures are those of ARP sheets 202-4302 and 202-4702; for everything else in the procedure, including the manufacturer's recommended tightening order, the official sheet prevails. Read the ARP 202-4302 instruction sheet; Read the ARP 202-4702 instruction sheet

Technical guide

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

ARP undercut studs

On an undercut stud, ARP reduces the shank between the two threads. The studs then stretch more evenly from one to the next: the clamping force becomes more consistent and compensates for head gasket compression at installation, which reduces the risk of a blown gasket.

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
Block threads	Stressed at every tightening	Preserved: studs fitted by hand

When studs become necessary

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

• CA18DET or CA16DET pushed, or CA18DE turbocharged: cylinder pressure 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 turbo or tuned CA, the standard fasteners soon reach their limit and the gasket is the first to suffer. 7/16 in 8740 studs keep their preload at much higher pressures, for a price out of all proportion to a cylinder head to be skimmed or an engine to be rebuilt.