Many drivers are familiar with the most common engine layouts used in modern vehicles, such as the V8, V6, and inline-4. Each of these terms refers to both the number of cylinders as well as the alignment of the pistons. For example, V6 motors consist of six cylinders split between two banks that angle away from each other, creating the “V” shape we use to identify the engine.
While engines like these have become the most common among manufacturers today, some more unique engine designs have stood the test of time for certain brands. One of the most notable examples of this is the Subaru Boxer engine, which has seen use in nearly every Subaru platform in the last few decades.
What is a Boxer Engine?
Similar to how “V” and “I” denote the shape of the motor’s layout, the Boxer name tells you a lot about how the engine is configured.
Boxer engines use two opposing banks of cylinders, much like their V-shaped counterparts. However, the cylinder banks of Boxers are laying completely flat at a 180-degree angle rather than the 90-degree angle of “V” engines. This is where the name Boxer originated from, as the outward punching motion of the pistons resembles a prizefighter throwing punches during a fight.
Boxer vs. Flat Engines
This engine configuration is sometimes referred to as a “flat” engine, but inherent differences exist between a Boxer and many other flat-fours. While all Boxers are flat engines, not all flat engines are Boxers.
While both Boxers and regular flat-fours share the same piston layout, their firing order is dramatically different. Boxer engines have individual rod journals, which allow for both cylinder banks to mirror each other. Regular flat-fours instead have shared rod journals, which force the opposite pistons to move together in unison. For example, when a Boxer extends a piston on one side, the opposite piston also extends. On the other hand, when a piston extends in a flat-four, the opposite piston is forced to retract due to the shared rod journal.
Although select other manufacturers, such as Porsche, use flat-six and flat-four Boxer engines in a few vehicles, the Subaru Boxer exists solely as a four-cylinder design and is widely considered Subaru’s premier engine platform. The Boxer has gained a cult following over the years due to its inclusion in legendary Subie vehicles such as the WRX STI and Forester.
Benefits of Boxers
The Boxer design brings some real benefits to the table that you’d be missing with more traditional “V”, inline, or even flat motors.
For one, the 180-degree layout keeps the vertical profile of the engine short, which causes the center of gravity to be lower than with a taller engine. This provides better handling and responsiveness as the vehicle has less sway and body lean to mitigate.
The counter-punching motion of boxer engines also helps keep the engine smooth, with the extension of one bank’s cylinders canceling out the force of the opposite bank. Boxer engines are one of the few that are considered to be perfectly balanced. Compare this to a traditional flat-six, which experiences imbalance due to the odd number of cylinders on each bank as well as the inability of opposite-facing pairs of pistons to extend in unison. This balance is the main benefit of the Boxer design over other flat engines, as non-Boxer flat engines are unable to balance out their horizontal forces to the same degree.
Though it may not be a metric we traditionally measure engines by, the Boxer has gained quite a reputation for its unique exhaust note. Unequal-length headers give the motor its low rumble and throaty sound rather than the smooth note of equal-length designs. This distinctive exhaust noise has been affectionately nicknamed “the Subie rumble” by enthusiasts and fans.
Subaru Engine Services in Boulder
Whether your Subaru has a boxer or not, the specially-trained technicians at Super Rupair have the experience and equipment required to properly diagnose, service, and repair your vehicle! Our team knows every Subaru platform inside and out, giving you peace of mind that your vehicle is in the proper hands. Give us a call or schedule an appointment online today!