Reinforced head gasket Hyundai Kia 3.8 V6 G6DA

The Hyundai and Kia engines covered

The G6DA petrol engine, a V6 of 3.8 litres, powers several Hyundai and Kia models in the compatibility table below. It takes two head gaskets, one per cylinder bank.

The original gasket carries the part number 22311-3C240. Its bore is 97 mm; the manufacturer publishes neither its construction nor its thickness. It is sized for standard combustion pressure: if the pressure rises, the clamping load relaxes, the cylinder head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

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

This page brings together 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 98 mm, 1 mm larger than the original gasket, and the thickness offered is 0.81 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 both part numbers, one for each side.

Technical specifications

Gasket volume refers to the space the gasket leaves free above each cylinder. It adds to the volume of the combustion chamber and reduces the compression ratio, the more so as it is large. Only compare these values between gaskets of the same bore.

Preparation and fitting

Before fitting, check the flatness of the cylinder head and block with a straight edge, then have them resurfaced if necessary. These gaskets go on without sealing paste, since Cometic supplies 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 98 mm only.

Choosing bore and thickness

Gasket bore. The Cometic MLX only exists here in 98 mm (C4632 and C4633).

Thickness. The manufacturer does not publish any thickness for the original gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As the original thickness is not published, use a dial gauge to measure how far the pistons protrude above the block, all the more after resurfacing: that figure sets the clearance left between piston and cylinder head.

The brand

Cometic Gasket, Inc. is an American company, created in 1989 and based in Concord, Ohio, that designs gaskets and sealing solutions for engines. Its know-how rests on the gasket made to order, at the bore and thickness wanted. All its 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 97 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: 22311-3C240.

Important: the part numbers on this page only suit the G6DA engine, which takes two gaskets, one per cylinder bank: check your vehicle's engine code before ordering. Supplier designations: C4632-032 for the left side, C4633-032 for the right side.

Why switch to a reinforced gasket?

When the original gasket reaches the end of its capacity, the reinforced gasket takes over: under higher combustion pressure, it stays true to its shape instead of being crushed.

When power goes up, through a turbo, a supercharger or a raised compression ratio, the head gasket is the first link to fail in the top end. Moving to a reinforced gasket means choosing safety over comfort: it spares you the breakdown and the cylinder head removal that follows.