Third-generation Subaru four-cylinder boxer engine

Third-generation Subaru four-cylinder boxer engine

Subaru has unveiled today the third and latest generation of its trademark horizontally opposed or ‘boxer’ engine, the first major redesign in 21 years. The first Subaru boxer engine was introduced in the Subaru 1000 back in 1966. Since then, the basic engine design has been refined and updated, with current versions now offered with turbocharging and engine stop-start technologies.

The latest engine is almost entirely new yet it maintains all the advantages of the horizontally-opposed layout: lightweight, compact, low center of gravity, and superior vibration balance. The key difference between it and previous designs is the environmental factor; it is roughly 10 percent more fuel efficient than the four-cylinder unit it replaces in Subaru’s lineup.

Peak output stands at a relatively unexciting 146 horsepower and 145 pound-feet of torque but the engine has been designed with consideration of the technology’s expandability and potential capability to receive further upgrades.

Engineers have reviewed the bore and stroke of the basic structure to allow a longer stroke than current engines. It is designed to achieve high efficiency in basic performance, allowing the smooth and sporty rotational properties for which horizontally-opposed engines are known, while also making improvements in practical torque and environmental friendliness.

It comes in two guises, 2.0 or 2.5-liters, and can be matched with either a manual or continuously variable transmission. Production will take place at Subaru’s new Gunma Oizumi plant in Japan, with the first versions to appear in the Subaru Forester by the end of the year.