Chapter 09: Final Review & Key Terms

1.1. Key Terms

compacted graphite iron (CGI) A material produced from powdered iron alloys squeezed into molds at high pressures and then heated to bond the metal particles together; also known as sintered graphite.

creep The movement of a cylinder head across the cylinder block deck when thermally cycled. When heated and cooled, the head expands and contracts at a different rate across the block deck by sliding over the head gasket.

cross flow cylinder head A head design with the intake and exhaust manifolds located on opposite sides of an in-line engine to improve engine breathing characteristics.

cylinder head gasket The component that maintains the seal around the combustion chamber at peak operating temperatures and pressures and that keeps air, coolants, and engine oil in their respective passages over all temperatures and pressures.

in-block camshaft An engine that has only the valves, rocker levers, and bridges located in the cylinder heads above the piston; the camshaft is located in the engine block. The cam may be a low- or high-mounted type; also known as a pushrod engine.

multilayer steel (MLS) gasket A method of sealing the cylinder head to the engine block using multiple thin layers of cold-rolled, spring-grade stainless steel coated with elastomeric (rubber) material.

overhead camshaft engine An engine that has the camshaft located in the cylinder head.

parallel flow head A head design that features intake and exhaust manifolds on the same side of the engine and short, large ports that are joined together to provide a more compact engine design with adequate airflow to the cylinders; also known as the uniflow design.

reverse flow cylinder head A cylinder head with no exhaust manifolds on the outside of the cylinder head; instead, short exhaust runs are fed directly to the turbocharger located in the V between the cylinder banks.

scissor gear Two separate, spring-loaded gears incorporated into a single drive gear that meshes under tension with a drive gear with no clearances. The gear is designed to reduce noise from gear rattle caused by torsional vibration.

torque-to-yield (TTY) bolts Cylinder head bolts that are tightened past their yield strength or elastic point; when tightened to specification, they stretch to a point just over precisely calibrated yield strength and not to the tensile where the bolt will break.

torque-turn method A method that requires a bolt to receive an initial preload using a torque wrench; afterward, the bolt is turned several additional degrees, flats, or turns; also known as the torque-plus-angle method.

torsional vibration The speeding up and slowing down of the crankshaft caused by alternating compression and power strokes of the engine cylinder.

Tyndall blue The blue-colored exhaust smoke created by a wavelength of light passing through microscopic-size exhaust particles. Oil and fuel droplets in the exhaust most frequently create the blue tint in the exhaust smoke.

valve overlap The angle in crankshaft degrees at which both the intake and the exhaust valves are open; overlap occurs at the end of the exhaust stroke and at the beginning of the intake stroke.