Now that we understand how the combustion process
works we need to learn WHERE it works, i.e., inside the
engine. The engine cylinder doesn’t live outside in
space, its usually made of some kind of metal- iron,
steel, or aluminum. In most automobile engines, the
cylinder is created when a cylinder bore is cut out of a
block of cast metal (the engine block). The piston will
then travel within the cylinder bore, and attach to the
crankshaft which spins alongside or below the block.
The other moving parts of the engine like the camshaft
and valves are likewise located within or around the
same metal engine block.
The walls of the cylinder have to be strong, in order to
withstand the explosive power of combustion, and to
withstand the wear and tear of repeated 4 stroke piston
cycles. Therefore, the walls of the cylinder have to be
thick enough to provide the necessary strength.
However, thick walls come at a cost: added weight. The
heavier engine, the harder it is to move it. When the
engine powers a car, the heavier the car the slower it will
accelerate and longer it will take to slow down. So extra
weight is bad for cars. As a result, engines are built with
enough strength while minimizing weight.
Cylinders are often located together in a single engine
block, and they share a single crankshaft, like the pedals
of a bicycle. Some engines have all or some of the
cylinders sharing the same camshaft, with the cam lobes
for each cylinder located along the length of the shaft
corresponding to the cylinder location.
With combustion occurring more than a thousand times
a minute, the engine block gets quite hot, not to
mention the heat created from friction of all the moving
parts. So how do we get rid of that heat and relieve the
friction? With water and with oil.
Engine block diagram-internals of a 4 cylinder overhead