The way engine cylinders are arranged is called the engine configuration.
Tilting an engine reduces its height. This can reduce the height of the bonnet as well, which allows a more streamlined body shape.
Tilting can be carried to an extreme by lying the engine completely on its side. It is then called a flat engine. This greatly reduces engine height.
As the number of cylinders increases, the length of the block and the crankshaft can become a problem. One way to avoid this is with a V configuration. This design makes the engine block and the crankshaft shorter, and more rigid.
In vehicle applications, the number of cylinders can vary, usually from 4, up to 12.
Common angles between the banks of cylinders are 90 degrees and 60 degrees.
V-type engines are wider than inline engines, and may also be lower.
Horizontally-opposed engines have 2 banks of cylinders, 180 degrees apart, on opposite sides of the crankshaft. A useful design when little vertical space is available. It is shorter than a comparable in-line engine but wider than a V-type.
A rotary engines uses a rotor in a housing, instead of a pistons in a cylinder. This provides a very compact power unit.
