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A look inside Subaru’s ‘boxer’ engine

To most people, a boxer is someone who makes his living in the ring. But there’s another definition in the automotive world — it’s a type of engine, and the only kind you’ll find in a Subaru vehicle.

“It’s also called a horizontally opposed or flat engine,” says Ted Lalka, vice-president of product planning and marketing for Subaru Canada.

“They tend to be compact and lightweight, and they produce a fair amount of power to weight. They’re still used in aviation for those reasons, and our company has a background in the aircraft industry, so we developed an expertise in these types of engines.”

The heart of an engine is a large, heavy shaft called the crankshaft. It’s attached to pistons, which slide inside cylinders when they’re powered by the exploding force of gasoline that’s been detonated by the spark plugs. The pistons turn the crankshaft, and its spinning motion is what ultimately turns the car’s wheels.

It’s similar to the way your legs move up and down to turn the pedals on a bicycle, with that power used to turn the wheels.

On most engines, the pistons are above the crankshaft, either in a straight line (called an inline engine, the most common configuration for four-cylinder engines), or slanted in two banks, forming a V that gives V6 and V8 engines their names. But on a boxer engine, the four or six pistons lie flat on either side of the crankshaft, where they move horizontally in their cylinders to provide power.

A boxer engine isn’t as tall as a regular engine, which helps to lower the vehicle’s centre of gravity. This improves handling and stability.

“With the boxer engine, it has very good balance between the left and right side, so the vehicle handles in a very predictable manner,” Lalka says. “In addition, it makes servicing the vehicle easy. A lot of the components can be placed on top of the engine, so the alternator, water pump, and even the oil filter are right on top where they’re easier to reach.”

Several companies have used the boxer engine design over the years. Porsche currently uses it in the 911, Boxster and Cayman. Other cars that have used it in the past include the Chevrolet Corvair and original Volkswagen Beetle.

A different type of engine

  • The boxer engine is part of Subaru’s “symmetrical” all-wheel drive configuration, in which all driveline components are aligned on the car’s north-south axis for better balance.

  • It’s believed that horizontally opposed engines got the name “boxer” because the piston movement looks like boxers jabbing at each other.

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