Flat-Out Power

4/7/2017

Version 14.1

The SUBARU BOXER delivers a one-two combo of performance and torque.

You feel it when you aim your WRX, STI or BRZ into a curve: that crisp, precise response to steering inputs and quick turn-in that make the car feel so connected to the road. Body structure, drivetrain, suspension, steering and tires all play their roles. Yet, you’re also feeling something bigger at the core of your vehicle’s nimbleness, and indeed, the core of the brand: the SUBARU BOXER engine.

Subaru introduced its first horizontally opposed engine a half-century ago, and mechanical evolution has greatly increased performance and efficiency since then. The reasons Subaru adheres to this configuration, and the benefits that all Subaru drivers get from it, however, remain the same.

Low and Steady 

By the time America saw the Subaru 360 minicar in 1968, the company had already steered toward its future. In 1966, Fuji Heavy Industries Ltd. debuted the 1000, and under the hood beat the new heart of Subaru, a 1.0-liter 4-cylinder engine – but not with a conventional inline design. Subaru instead employed a horizontally opposed layout. In this type of engine, or flat engine, the cylinders lie in a 180-degree plane, giving the engine the “flat” nickname. It’s also called a “boxer,” because the pistons on opposite sides of the engine move toward and away from one another like a boxing match.

The boxer engine’s low, compact form made it ideal for packaging in a small car. Just as critically, Subaru engineers favored a boxer because it enhanced stability by lowering the vehicle’s center of gravity relative to taller inline-type engines. That trait, along with a symmetrical layout providing excellent left-right balance, remains key to flatter cornering and superb agility in Subaru vehicles to this day. In choosing the boxer, those pioneering engineers had unwittingly created the basis for all things performance-related as well as just plain flat fun for Subaru enthusiasts.

Other boxer benefits realized 50 years ago endure. The “boxing” motion of the pistons canceled out certain vibrations that affected inline 4-cylinder engines of the era. Today, SUBARU BOXER engines don’t require a balance shaft to mitigate vibration, as some contemporary inline engines do. 

An All-Wheel Drive Natural

In the early ’70s, Subaru engineers found yet another advantage to the boxer design – and it was significant. The Subaru engine was mounted longitudinally (front to back) instead of transverse (sideways – as in many front-wheel drive cars), with the transmission located directly behind it. 

That layout made it relatively easy to adapt a driveshaft in a straight, near-horizontal line to the rear wheels to enable the company’s first four-wheel drive models – and later, Symmetrical All-Wheel Drive.

It’s been a winning combo ever since.

The SUBARU BOXER Evolution

Because the boxer engine was so compact and low, the car’s spare tire fit under the hood, which increased luggage space. Subaru vehicles used this feature into the early 1990s.

Introduced in 1966, the first SUBARU BOXER engine was a 977-cc 4-cylinder unit with 55 hp.
In the early 1970s, Subaru advertising called the 4-cylinder boxer engine “quadrozontal.”
The first turbocharged SUBARU BOXER was used in 1983.
1980s: The first turbocharged SUBARU BOXER was used in 1983.
The first 6-cylinder SUBARU BOXER was a 145-hp 2.7-liter unit in the 1988 XT6 sports coupe.
1980s: The first 6-cylinder SUBARU BOXER was a 145-hp 2.7-liter unit in the 1988 XT6 sports coupe.
The FA Series 2.0-liter boxer engine in the BRZ produces 100 hp per liter without a turbo.
2010s: The FA Series 2.0-liter boxer engine in the BRZ produces 100 hp per liter without a turbo.