Subaru Boxer Engines Explained

Certain automotive manufacturers have developed a reputation for using specific engines or technologies in their vehicles, such as Porsche’s flat-sixes or Dodge’s supercharged V8s. One of the most notable examples of a brand that’s known for its unique motors is Subaru and its legendary boxer engine configuration. Subaru is currently the only brand to employ boxer-four engines besides Porsche, who use a similar engine in their entry-level 718 platform.

From the WRX to the Forester, almost every single Subaru platform uses this specific type of engine. In this article, we’ll cover the benefits of boxers, how they work, and why Subaru is virtually the only manufacturer to make use of them.

Boxer engine in Subaru BRZ engine bay

What is a Boxer?

The defining feature of the boxer layout is its horizontal piston configuration. Rather than having two banks of cylinders with a slight angle away from each other (“V” Layout) or all cylinders in a row (“inline” layout), boxer engines instead lie the pistons completely flat. 

Boxers aren’t the only engines to use a 180-degree angle, as flat engines like the flat-six also employ a similar design. What separates boxer engines from other flat motors is the simultaneous movement of opposing pistons. This unique trait is also where the engines get their namesake, as the movement of the pistons in a boxer resembles the outward punching motions of a boxer’s gloves. 

Animation showing horizontal movement of boxer pistons
Gabriel h 011, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Why Does Subaru Use Boxers?

Since 1966, the boxer has been a mainstay in the Subaru model lineup despite very limited adoption from other automakers. What makes the boxer Subaru’s preferred choice?

For one, the small package of a four-cylinder boxer allows the engine to be used in the vast majority of engine bays where other motors may not fit. Since the pistons take up less space horizontally as well, the center of gravity is improved by the flat engine design which leads to superior handling and control. 

The flat layout also provides a direct output of power to the transmission, rather than losing efficiency with the extra components needed in other types of engines. 

While this isn’t a trait specific to boxers, these motors have a perfect balance due to the counteracting forces of each combustion stroke canceling each other out. This significantly mitigates the engine’s vibrations compared to those produced by unbalanced motors such as V6s. 

Disadvantages of Boxer Engines

While boxers bring a multitude of benefits to the table, they aren’t perfect by any means. Here are some downsides of using these motors.

  • Difficult to access for maintenance or repair
  • Takes up more space horizontally
  • The unique size constraints and layout simply don’t make sense in certain engine bays (many Subaru models have their engine bays designed around the boxer rather than trying to retrofit)

Subaru Services in Tucson

If you’re looking for top-notch Subaru service or repair in the Tucson area, trust the specially trained technicians at Micro Import Service! Our team has extensive experience working on all types of Asian import vehicles, including Subaru boxer engines. Whether your Subie needs an oil change or a head gasket, we have you covered. Give us a call or schedule online today!