What Is a Boxer Engine?

Posted on: September 15, 2020, by :

A “boxer” engine is one with cylinders positioned horizontally instead of vertically — the latter configuration found in inline and V-type engines — and the pistons move in the opposite direction from each other.

A boxer engine illustration

The official engineering term for these engines is horizontally opposed, but they are called “boxer” engines because the horizontal movement of the pistons resembles the actions of a boxer’s fists.

They also are called “flat” or “pancake” engines because they are shorter in height compared to inline and V-type engines. This gives boxer engines a lower center of gravity, which engineers say improves a vehicle’s handling. One drawback of boxer engines is that access to some components for mechanics may be restricted compared to, say, an inline four-cylinder that is more upright.

Currently, Porsche, Subaru and Toyota are the only manufacturers that offer “boxers.” The Porsche 911 has always come with boxer engines, and the current lineup has a variety of six-cylinder versions (or flat-sixes). The Porsche 718 Boxster, 718 Cayman and 718 Spyder have four-cylinder boxers (flat-fours).

All current Subaru engines are the horizontally opposed type with four cylinders. The Toyota 86, a mechanical twin of the Subaru BRZ, also uses a flat-four Subaru engine.

Whether a boxer engine has four or six cylinders, half the pistons face in one direction and half in the other, and they move inward and outward at the same time.