Engine Basics: V-what?

What do all those names and numbers associated with my engine mean? This is a pretty common question, and I’ll do my best to succinctly answer it. First of all, there is the configuration of your engine. For example, there is the “V8.” The letter “V” describes the layout of the engine. With only one exception (the Mazda ‘Wankel’ motor, which is probably a good subject for its own entry), all modern gas and diesel cars have pistons that move within cylinders to generate power.


This is a V-8 engine. You can see the two banks of cylinders, 4 in each, arranged in a V and connected at the bottom.

In a V8, there are two banks of 4 cylinders, which attach at the bottom to form a “V.” The most common configuration is an “I4,” which means “inline 4 cylinder.” Think half of a V8 and you get the picture. V6 engines are two banks of 3 cylinders, and I6 motors are one long bank of 6 cylinders. So far, so good.



In this image, looking down from the top, you can see the 6 cylinders in a row - this is an inline-6 engine.


Then there is the displacement, which is measured (at least with modern cars) metrically. That is, in liters. It is a basic measure of the size of the motor – the larger the displacement, the more power you theoretically can make. So a 1.8 liter I4 engine probably makes less power than a 4.5 liter V8. It’s a quick way to compare engine power. It also affects fuel economy – bigger engines drink more gas.

How do they measure displacement? There's a mathematical formula that I won't pretend to understand, but the concept is kind of simple. Imagine you filled the cylinders of the engine with a liquid, and then poured it into a big container and measured it. That gives you a pretty good sense of the size of the engine. And as I mentioned, size and power are usually directly related.

More on Engine Basics to come!