Figure 3-9.Cylinder heads.
of aluminum since it needs the ability to dissipate large
amounts' of heat. On air-cooled engines, the oil pan
usually is made of cast aluminum, and it is covered with
cooling fins. The oil pan on an air-cooled engine plays a
key role in the removal of waste heat from the engine
through its lubricating oil.
The cylinder head (fig. 3-9) provides combustion
for the engine cylinders. It is built to conform to the
In liquid-cooled engines. the cylinder (fig. 3-10)
arrangement of the valves: L-head, I-head, or others.
head is bolted to the top of the cylinder block to close the
Cylinder heads on liquid-cooled engines have been
made almost exclusively from cast iron until recent
years. Because weight has become an important
consideration, a large percentage cylinder heads now
are being made from aluminum. The cylinder heads on
air-cooled engines are made exclusively from
aluminum. This is due to the fact that aluminum
conducts heat approximately three times as fast as cast
iron. This is a critical consideration with air cooling.
Figure 3-10.Cylinder head for L-head engine.