Athena Cut Ring Racing Head Gasket Without Rings 1.8mm x 87.1mm BMW Cut Ring Head Gaskets 5150 AutoSport BMW M20 Cut Ring Head Gasket by Athena SCE BMW S54B32 M3 E46 Z3 Z4 ATHENA Cut Ring Head Gasket 1.2mm 87 Cut Ring Head Gaskets 5150 AutoSport. This M20 Head Gasket is specifically engineered to replace BMW part numbers 11121722734, 11121722735, 11121722737, and 11121722738 for the M20B20, M20B23, M20B25, and M20B27 engines used in a variety of BMW models, including the E12, E21, E28, E30, and E34. Factory OEM & MLS head gaskets are only engineered to handle a limited amount of cylinder pressures before they start to leak, causing a range of issues, including engine overheating, loss of power, misfires, and in severe cases, catastrophic engine failure. Athena SCE Cut Ring Head Gaskets are uniquely designed to handle increased cylinder pressure caused by power modifications, making them the recommended choice for applications making 16+ psi. Design: Athena SCE's gasket body is composed of Motorgasket, a reinforced material developed by Athena's R&D department. This consists of a steel core covered with two layers of asbestos free aramid fibre and offers excellent thermal and mechanical resistance without compromising its ability to adapt to mating surfaces. To ensure maximum sealing under all conditions, a silicone bead is also applied to critical sealing areas, such as oil and coolant passages. The AISI 304 stainless steel cooper rings bite into the aluminum head, providing maximum sealing around the cylinder bore and optimizing engine performance, even on engines with nitrous and or turbo applications that exceed 2 bar boost. Please be aware that the gasket should be 0. 5mm to 1mm larger than the piston. For example, if the piston measures 84. 5mm, then the gasket should be the next size up, either 85mm or 85. 5mm. Installation instructions: Make sure that the engine block and cylinder head surfaces are clean, flat, and free from any debris, oil, or coolant. Install the Cut Ring gasket on the engine block and ensure that it is properly aligned. Avoid twisting or bending the gasket during installation. Place the cylinder head on top of the gasket and install the head bolts or studs in their correct positions. Follow the manufacturer's recommended torque specifications and tighten the bolts or studs in the proper sequence to ensure even clamping force across the gasket. After the initial tightening, re torque the head bolts or studs after the engine has been started and then allowed to cool to room temperature. This will ensure that the gasket is properly seated and compressed. It is recommended to not use any additional sealant on the gasket; it is already coated with a silicone bead sealant. Using additional sealant can hinder the performance of the gasket. Notes on Preparation and Installation: Before installation, it is crucial to have the mating surfaces of both the cylinder head and the block professionally cleaned and resurfaced to ensure they are completely flat straight. It is the responsibility of the engine builder to measure each cooper ring height and verify uniformity across all rings. After initial assembly, it is necessary to allow the engine to complete a full heat cycle, then re torque your head studs to spec. This means allowing the engine to warm up to its normal operating temperature, remain at operating temperature for several minutes to ensure each component is uniformly heated, then turned off and cooled completely to ambient temperature. BMW M20B20 Applications: BMW 3 Series 1977 1982 BMW E21 320i 1982 1990 BMW E30 320i BMW 5 Series 1981 1987 BMW E28 520i 1988 1992 BMW E34 520i BMW M20B23 Applications: BMW 3 Series 1977 1982 BMW E21 323i 1982 1984 BMW E30 323i BMW M20B25 Applications: BMW 3 Series 1985 1991 BMW E30 325e 325i 325is BMW 5 Series 1988 1992 BMW E34 525i BMW M20B27 Applications: BMW 3 Series 1982 1987 BMW E30 325e BMW 5 Series 1982 1988 BMW E28 525e 528e