Reinforced head gasket Toyota 1ZZ-FE

The Toyota engines covered

The 1.8-litre 1ZZ-FE petrol engine, a four-cylinder, sits under the bonnet of the Toyota Corolla, Avensis, Celica, Matrix, MR2 and several other models, listed below.

The original gasket carries part number 11115-22030. Toyota publishes neither its bore, nor its thickness, nor its construction. It is calibrated for the standard combustion pressure: as soon as that pressure climbs, the clamping load sags, the cylinder head gains play on the block and coolant makes its way into a cylinder.

Reinforced cylinder head gaskets

The gasket does not seal on its own: the fasteners clamping the head to the block provide half of the sealing. Beyond 100 N/mm² of stress, a composite gasket settles for good; the 301 stainless steel of MLS gaskets reaches 517 N/mm², 5 times more, and recovers its shape with every combustion.

This page groups two Cometic part numbers, from an American maker of competition gaskets, in MLS construction: C4496 with an 80 mm bore and C4497 with an 82 mm bore. Eighteen thicknesses are offered for each, from 0.69 to 3.56 mm. It is customary for the gasket bore to exceed the cylinder bore by at least 0.5 mm. Each gasket is sold individually, one gasket per engine.

Technical specifications

A gasket's volume is the empty space it leaves above each cylinder. It adds to the combustion chamber and reduces the compression ratio; only gaskets of the same bore can be compared.

Preparation and fitting

Before fitting, lay a straightedge across the cylinder head and the block, and have any warped surface machined. Cometic supplies this gasket already coated: do not add any sealing paste.

Technical guide

The construction offered

MLS Cometic Embossed stainless steel plates, stacked and then riveted together. The outer plates carry active beads around each cylinder and each fluid passage. A moderate clamping load is enough to seal, and the bore barely distorts. A versatile gasket, from the tuned naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS gasket comes in 80 mm (C4496) and 82 mm (C4497), with no other bore.

Thickness. Toyota discloses no 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.

Because the original thickness is not published, measure with a dial gauge how far the pistons protrude above the block face, especially if you are aiming for a thickness below that of the removed gasket: that reading gives the real distance between piston and cylinder head.

The brand

Cometic Gasket, Inc., an American maker of gaskets and sealing components for engines, was founded in 1989 in Concord, Ohio. It owes its reputation to the made-to-measure gasket, cut to the required bore and thickness, and to production that is entirely American, from local raw 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 80 and 82 mm bores of the gaskets offered 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: 11115-22030.

Important: the two part numbers on this page fit the 1ZZ-FE engine: confirm 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 takes over: under higher combustion pressure it does not crush and keeps its geometry.

Fitting a turbo or a supercharger, or raising the compression ratio, loads the head gasket first, the weak link of the top end. A reinforced gasket rules out the leak and the cylinder head removal it forces, a job out of all proportion to the price of the gasket.