Subaru “Boxer” Engine Turns 50

This week Subaru-maker Fuji Heavy Industries Ltd. celebrates the 50th anniversary of the launch of its first vehicle equipped with a “boxer” type engine with horizontally opposed pistons.

The carmaker says it has produced more than 16 million boxer engines since then, including gasoline and diesel mills. The only current Subaru vehicle that isn’t powered by a boxer engine is the Japanese-market Justy small hatchback, which is built under contract by Daihatsu Motor Corp.

Karl Benz patented the boxer engine design, which he called a “kontra engine,” in 1897. While several carmakers have used such engines over the years, Subaru and Porsche have been the biggest proponents and currently are the only ones still using boxer powerplants.

The boxer nickname comes from the punch-counterpunch motion of the pistons in the horizontally opposed layout. The design also is known as a flat or “H” type engine.

Benefits include a shorter length, good internal balance, a low center of gravity and more efficient cooling (on air-cooled motors) than traditional “V” and inline configurations. But boxer engines are wider and tend to be more expensive. Exhaust piping also is more complex.

The first Subaru vehicle with a boxer engine was the tiny 1000 sedan (shown above). The water-cooled flat-four generated 54 hp.

Boxer engines also have been used in motorcycles and small airplanes. These applications benefit from the engine’s lightweight design and smooth operation.