What Do Liters Mean in an Engine?

Engine size is measured in several ways, including cubic centimeters in small engines and most motorcycles, cubic inches in most American cars and liters in most foreign cars. This isn't a rule, however. American hot rods use liters as a measurement quite often. The size is representative of the displacement of the cylinders of the engine. Why engine displacement is displayed in specific ways is up to the manufacturer, but it often comes down to marketing which size sounds neater, bigger or more powerful.

Displacement

The displacement of an engine, or the engine's size, refers to the amount of space its cylinders take up. Often, this is measured in liters, especially for larger engines that are found in cars and trucks. An example would be the Ford Mustang's 5.0 liter engine. It is also commonly referred to as the 302 cubic inch motor. This simply means that the cylinder space of the engine displaces 5 liters or roughly 302 cubic inches. Naturally, cars with more cylinders will typically have larger displacements.

What Does Displacement Affect

Larger displacements typically mean more horsepower and more torque are generated from the engine, although this isn't always the case. Small displacement engines of today can fairly easily out power larger displacement engines of the past. Larger displacements also tend to note a higher cylinder count, although this isn't always true. Manufacturers such as Porsche tend to use smaller displacement cylinders in larger quantities, leading to small displacement engines with a higher cylinder count.

Can You Get More Displacement

For those wishing to produce the most power possible from an engine, increasing the displacement is always an option. This is done by boring out the cylinder walls and putting in thicker pistons, and also by installing a longer stroke crank, which causes the pistons to travel farther. The popular Chevy 383 is a Chevy 350 that has been bored and stroked to 33 inches of greater displacement.

Can You Have Too Much?

Can you have too much displacement? The short answer is no. The long answer is not that easy, of course. Larger displacement tends to mean bigger and heavier pistons that have to travel a farther distance. This kills rotational inertia and will result in a lower revving, a less "spunky" or "eager" engine, which can also mean it is less responsive. Taken to an extreme, this can result in a slower engine, and over boring an engine can weaken the cylinder walls.

Are There Replacements for Displacement?

There was an old saying in racing circles that "there's no replacement for displacement." While this may have been true in the past, with the increasing availability of inexpensive turbo and super chargers, this isn't always the case. Advancing technologies have put modern small displacement engines in competition with older, larger displacement engines. It is true that modern, large displacement engines with forced induction produce more power than small engines with the same advantages, but this is largely a result a better technology and not of the larger displacement.