Page 15 of catalogue Cylinder head gaskets of Reinz-Dichtungs-GmbH

DETERMINANT ENGINE PROPERTIES
VICTOR REINZ engineers consider the following engine-related properties when designing the functional elements of an MLS head gasket: ¬ Combustion type (spark ignition or diesel) ¬ Max. combustion pressure ¬ Cylinder head and block design ¬ Geometry, e.g. combustion chamber diameter ¬ Locations of coolant & oil channels ¬ Web widths ¬ Material (e-modulus, stiffness, hardness, and temperature coefficient) ¬ Roughness of the components ¬ Construction (closed deck, open deck, liners) ¬ Head Bolts quantity and location clamping force (tolerances) bolt torque (elastic or plastic) bolt / ignition force ratio Fb / Fignit ¬ Installed thickness ¬ Special requirements, e.g. solution for three-land junction VICTOR REINZ considers these functional elements, creating MLS designs that ensure maximum performance and service life under the strictest engineering conditions.

Head bolt / ignition force ratio An ideal MLS design is determined primarily by the clamped state of the »engine block - gasket - cylinder head - head bolts« structure. The design is also influenced by the bolt / ignition force ratio Fb / Fignit, which determines how much the bolt forces apply sealing pressure to counteract the combustion pressure. Thus, the ratio Fb / Fignit should not be less than 3.0 because otherwise the demands placed on the head gasket would increase disproportionately. This value is described as the gasket's safety factor. Furthermore, the ratio determines the outlay required to achieve optimum pressure distribution. During installation, the head gasket undergoes plastic and elastic deformation. However, the relationship of these two portions varies strongly depending on the MLS design, and therefore has an influence on the basic behavior of the entire sealed joint.

Bolt force / ignition force ratio

Bolt force / ignition force ratio

10 9 8 7 6 5 4 3 2 1 0 60 65 70 75 80

Diesel engines

10 9 8 7 6 5 4 3 2 1 0

Gasoline engines

85 90 95 100 Combustion chamber diameter in [mm]

60

65

70

75

80

85 90 95 100 Combustion chamber diameter in [mm]

Diesel engine (table at left) and gasoline engine (table at right). Challenge for modern automobile Engines: the increasingly unfavorable bolt force / ignition force ratio.

¬ 15