Reinforced cylinder head gasket Nissan Infiniti VR30DDTT

The Nissan engines covered

The Nissan VR30DDTT is the 3.0 litre twin-turbo petrol engine fitted to the Infiniti Q50 and Q60, the Nissan Skyline (V37) and the Nissan Z (Z34) in the compatibility table. It takes two cylinder head gaskets, one per cylinder bank.

These original gaskets carry the part numbers 11044-4HK0A and 11044-4HK0B. Nissan publishes neither the construction nor the thickness. They are rated for standard combustion pressure: once that pressure climbs, clamping load fades, the cylinder head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

A head gasket does not seal by itself alone: the seal depends on the fasteners, which press the head against the block. A composite gasket is crushed for good beyond 100 N/mm² of admissible stress, whereas the 301 stainless steel of MLX gaskets withstands 517 N/mm², 5 times more, and regains its shape at every combustion.

This page gathers the part numbers of Cometic, an American maker of racing gaskets, in a single construction: the MLX with its chamber stopper. The gasket bore is 88.5 mm, 1.5 mm larger than the original gasket, and the thickness offered is 0.91 mm, enough to adjust the compression ratio without touching the pistons or the cylinder head. As a rule, the gasket bore chosen is at least 0.5 mm larger than the actual cylinder bore. Each part number is sold individually; the engine takes two gaskets, one per cylinder bank, so order the part number for each bank.

Technical specifications

Gasket volume represents the free space the gasket leaves above each cylinder. That space adds to the combustion chamber: the larger it is, the more the compression ratio drops. Compare these values only between gaskets of the same bore.

Preparation and fitting

Before fitting, check with a straight edge that the cylinder head and block are flat, and have them skimmed if required. These gaskets are fitted without sealant, as Cometic delivers them already coated.

Technical guide

The construction offered

Cometic MLX A multi-layer stainless steel gasket whose folded centre layer forms a stopper around the combustion chamber, with a high-temperature coating. Clamping rises locally without adding to bore distortion. It is the most resistant of the all-steel gaskets, to be kept for severe boost; it is offered here in 88.5 mm only.

Choosing bore and thickness

Gasket bore. The Cometic MLX comes in 88.5 mm only.

Thickness. The manufacturer does not release the thickness of the original gasket. Fitting a thicker gasket increases the combustion chamber volume and lowers the compression ratio; a thinner one shrinks that volume and raises the ratio.

After skimming, use a dial gauge to measure how far the pistons protrude above the block: it determines the clearance that remains between piston and cylinder head.

The brand

Cometic Gasket, Inc. is an American company, founded in 1989 and based in Concord, Ohio, that makes engine gaskets and sealing solutions. It made its name with the gasket produced to order, in the bore and thickness wanted. Its whole production is American, from American materials.

Advantages over the original gasket

When a reinforced gasket becomes necessary

• Adding forced induction, or raising boost on an already turbocharged engine
• Cylinder rebored beyond what the 87 mm bore of the original gasket covers
• Looking for a compression ratio different from standard, higher or lower
• Engine that has already lost its gasket, or is consuming coolant
• Competition use, where the gasket goes through repeated temperature rises

Vehicle compatibility

OEM part number: 11044-4HK0A and 11044-4HK0B.

Important: the part numbers on this page only suit the VR30DDTT, which takes two gaskets, one per cylinder bank: check your vehicle's engine code before ordering. Supplier designations: C14147-036 for the right side, C14148-036 for the left side.

Why switch to a reinforced gasket?

Where the original gasket reaches its limit, the reinforced gasket takes over: at higher combustion pressure it holds its shape instead of being crushed.

As power progresses, through a turbo, a supercharger or a raised compression ratio, the head gasket is the first part of the top end to give way. Opting for a reinforced gasket means choosing safety over comfort: it avoids the failure and the head removal that comes with it.