Diesel Chapter 11-Cylinder Heads and Valve Train Mechanisms
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
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 more compact engine design with adequate airflow to the cylinders; also known as the uniflow design
cross-flow cylinder head
a head design with the intake and exhaust manifolds located on opposite side on an inline engine to improve engine breathing characteristics
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
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
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, and turns. Also called the torque plus angle method
in-block camshaft
an engine that has only the valves, rocker levels, and bridges located in the cylinder heads above the piston; the camshaft is located in the engine block. The cam may be low or high mounted type. Also called a pushrod engine.
overhead camshaft engine
an engine that has the camshaft located in the cylinder head
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
valve overlap
the angle in crankshaft degrees that both the intake and exhaust valves are open; overlap occurs at the end of the exhaust stroke and the beginning of the intake stroke.
cylinder head gasket
the component that maintains the seal around the combustion chamber at peak operating temperatures and pressures and keeps air, coolant, and engine oil in their respective passages all over temperatures and pressures.
torsional vibration
the speeding up and slowing down of the crankshaft caused by alternating compression and power strokes of the engine cylinder
scissor gear
two separate spring-loaded gears incorporated into a single unit to reduce gear rattle caused by torsional vibration
