Reinforced head gasket Subaru 2.2 EJ22T

The Subaru engines covered

The EJ22T is a 2.2 litre petrol engine with four horizontally opposed cylinders. The gasket maker lists it for the Subaru Legacy (1991 to 1994) in the compatibility table below.

The original gasket carries part number 11044-AA280. Subaru does not disclose its bore, thickness or construction. Like any flat engine, the EJ22T has two cylinder heads and therefore takes two gaskets. Sized for the standard combustion pressure, the original gasket gives way as soon as that pressure rises: the clamp load relaxes, the head lifts and coolant reaches a cylinder.

Reinforced cylinder head gaskets

Sealing does not rest on the gasket alone: it also depends on the fasteners that clamp the head to the block. A composite gasket is permanently compressed beyond 100 N/mm²; the 301 stainless steel of MLS gaskets withstands 517, 5 times more, and springs back at every combustion.

This page gathers 18 part numbers from Cometic, the American maker of racing gaskets, in a single construction: MLS, a multilayer steel design. All the part numbers (C4263) have a 98 mm bore; thicknesses run from 0.69 to 3.56 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 singly and covers one cylinder bank only: you need one gasket on the right and one on the left.

Technical specifications

A gasket's volume is the space it leaves open above each cylinder. It enlarges the combustion chamber and lowers the compression ratio. Compare only gaskets with the same bore: here every C4263 measures 98 mm.

Preparation and fitting

Before fitting, check the flatness of the head and the block with a straight edge and have whichever needs it resurfaced. Cometic gaskets arrive coated: apply no sealing compound.

Technical guide

The construction offered

Cometic MLS Several stainless steel sheets, stamped and riveted together. The outer sheets carry active beads around each cylinder and each fluid passage. Moderate clamping is enough to seal and the bore distorts little: a versatile construction, from the tuned naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS (C4263) is offered in 98 mm, with no other bore.

Thickness. No thickness is published for the original gasket 11044-AA280. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

For a thickness below the original, use a dial gauge to read how far the pistons stand above the block's gasket face: that figure gives the clearance left between piston and head.

The brand

Cometic Gasket, Inc., an American company founded in 1989 in Concord, Ohio, designs and manufactures engine gaskets and sealing parts. Its speciality is the made-to-measure gasket, cut to the bore and thickness requested and made in the United States 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 98 mm bore of these gaskets 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-AA280.

Important: the part numbers on this page suit only the EJ22T engine: check your vehicle's engine code before you order.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced one takes over: as combustion pressure rises, it holds its shape instead of being crushed.

When power goes up, through a bigger turbo, higher boost or a raised compression ratio, the head gasket becomes the weak point of the top end. The reinforced gasket prevents the leak and the head removal that follows, an operation far dearer than the part.