- Inline -- the cylinders are arranged in a line in a single bank:
- V -- the cylinders are arranged in two banks set at an angle to one another:
- Flat (also known as horizontally opposed or a boxer) -- the cylinders are arranged in two banks on opposite sides of the engine:
You can find, for example, inline 6 cylinder engines, flat 6 cylinder engines and V-6 engines. If you built all three of these six cylinder engines to the exact same specifications -- same displacement, same valves, same intake and exhaust systems, etc. -- they would likely perform nearly identically. Displacement is displacement.
However, there would be a number of differences between the engines in use. Here are several of them to give you a taste:
- An inline engine is long and narrow. In small cars in particular, a long, narrow engine mounted transversely can allow a very short hood. In an air-cooled engine, the inline configuration is sometimes harder to cool.
- A flat engine is wide and flat. This gives it a low center of gravity.
- A V engine is a compromise between the two. It tends to be more cubical in shape.
- The inline shape needs only half as many camshafts as a V configuration (if using overhead cams), which can lighten things slightly.
- There can be differences in the amount of metal required in the block, meaning that one type might be lighter than the other.
- There can also be cost differences during manufacture.
People sometimes get religious about engine configuration.
Check out these links for more information on engines: