Reinforced head gasket Subaru 2.0 EJ20 EJ201 EJ202 EJ204 EJ205 EJ207

The Subaru engines covered

The EJ20 is a 2.0 litre flat-four petrol engine, naturally aspirated for the EJ20, EJ201, EJ202 and EJ204, turbocharged for the EJ205 and EJ207. It powers the Subaru Impreza, Legacy, Forester, Outback, WRX and Exiga models in the table below. As it has two cylinder heads, it uses two head gaskets.

The original gaskets carry part numbers 11044-AA360 and 11044-AA364 (EJ20, EJ201), 11044-AA680 (EJ204) and 11044-AA482, 11044-AA483, 11044-AA650 and 11044-AA651 (EJ202, EJ205, EJ207). Subaru publishes neither their bore nor their thickness. They are sized for standard combustion pressure: when that rises, the clamping load drops, the head moves away from the block and coolant reaches a cylinder.

Reinforced cylinder head gaskets

Sealing does not rest on the gasket alone: the fasteners that clamp the head against the block play just as large a part. With the O-Ring, it is the stainless steel wire that seals the combustion chamber by itself, while the gasket body closes the water and oil circuits; with the MLS, the 301 stainless steel sheets withstand 517 N/mm², 5 times the stress at which a composite gasket compresses for good, and recover their shape with every combustion. The four part numbers on this page belong to one or other of these two constructions.

This page brings together four part numbers from Athena, an Italian maker of competition gaskets, in two constructions: the O-Ring, a reinforced asbestos-free body combined with separate stainless steel rings, with part number 330130R, and the MLS, a stack of stainless steel sheets, with part numbers 338460R, 338002R and 338001R. The bores are 93.5 mm for the O-Ring and 94 mm for the MLS, with thicknesses from 0.9 to 1.3 mm. As a rule, choose a gasket bore at least 0.5 mm larger than the cylinders. Each part number is sold individually; as the flat engine has two cylinder heads, two gaskets are needed.

Technical specifications

A gasket's volume is the space it leaves free above each piston. That space adds to the combustion chamber and lowers the compression ratio; here the three MLS gaskets share the 94 mm bore and compare directly by thickness, while the O-Ring has a 93.5 mm bore.

Preparation and fitting

Before assembly, rest a straight edge on the head and then on the block to check their flatness, and have them resurfaced if necessary. Athena gaskets arrive ready to fit: do not add any sealing paste. This applies to each of the two cylinder heads of the flat engine.

Technical guide

The two constructions offered

O-Ring / Cut Ring Athena A steel sheet dressed with asbestos-free aramid fibre, around which a stainless compression wire is crimped at each cylinder. The wire transfers the clamping load to a thin band, at the exact spot where the seal is won or lost, and a silicone bead preserves the water and oil passages. This construction copes best with extreme combustion pressures and suits the most heavily loaded engines. Here, it is part number 330130R, in 93.5 mm.

Athena MLS A stack of two to five AISI 301 stainless steel sheets, laser cut, stamped and then riveted. A folded sheet encircles each cylinder and forms a Gas Stopper, which directs the clamping load towards the combustion chamber, while raised beads separate the water and oil circuits. The outer faces receive a coating: one layer withstands heat and fills small flaws in the block and head, a silicone layer stops the gasket from sticking at removal. It is Athena's all-steel solution, from the prepared naturally aspirated engine to moderate boost. Here, these are part numbers 338460R, 338002R and 338001R, all in 94 mm.

Choosing bore and thickness

Gasket bore. The Athena O-Ring (330130R) comes in 93.5 mm and the Athena MLS (338460R, 338002R and 338001R) in 94 mm.

Thickness. Subaru publishes no thickness for the original gaskets of these engines. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

With the original thickness left unstated, use a dial gauge to measure how far the pistons stand proud of the block's gasket face, especially if you aim for 0.9 mm: it sets the clearance left between piston and head.

The brand

Athena S.p.A. is an Italian company specialising in gaskets and engine parts. Its head office and main plant are in Alonte, in the Veneto; it also has sites in Spain, the United States, Brazil and India. Several car makers fit its multi-layer gaskets as original equipment, and the entire competition range is designed and made in Italy. Part numbers 330130R, 338460R, 338002R and 338001R are the ones on this page.

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 bore of the gaskets offered (93.5 and 94 mm) 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-AA360 and 11044-AA364 (EJ20, EJ201), 11044-AA680 (EJ204), 11044-AA482, 11044-AA483, 11044-AA650 and 11044-AA651 (EJ202, EJ205, EJ207).

Important: the part numbers on this page only apply to the EJ20, EJ201, EJ202, EJ204, EJ205 and EJ207 engines: note your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches the end of its capacity, the reinforced gasket replaces it: under higher combustion pressure it does not compress and keeps its shape. The Subaru EJ20 engines get four part numbers here.

As soon as a turbo engine gets more boost pressure or a raised compression ratio, the head gasket becomes the first weak link of the top end. A reinforced gasket prevents the leak, and with it the head removal that follows, an operation far more costly than the part itself. This holds for the turbocharged EJ205 and EJ207 as for any hard-driven engine.