How Does a Subaru Boxer Engine Work?

All Subaru vehicles contain the uniquely engineered Subaru Boxer engine.  The engine is known for its poise with respect to power and efficiency.  Rather than increasing engine power by increasing the number of cylinders, the Boxer engine uses an ingenious engineering design to increase energy output. 

The Boxer engine operates with increased efficiency and engine power through the use of two design techniques.

1. Horizontal engine design


2. Low profile or center of gravity

Horizontal Engine Operation

1. The boxer engine was designed to lie flat, with the cylinders in alignment with the drivetrain.  Sets of cylinders face opposite directions, either two sets of two or three sets of two depending on engine size.


2. As the crankshaft turns, the pistons push the cylinders directly toward their corresponding drivetrain components.


3. This design eliminates the need for additional parts to connect the action of the cylinders to the drivetrain.  Fewer components to power mean greater efficiency.  

The boxer engine is also called a flat engine, as opposed to V or in-line.  Subaru produces three types of engines for its vehicles; the basic Boxer engine, the 2.5 L flat 4 cylinder and the 3.6 L flat 6 cylinder.  Each is engineered with the horizontal design.

Low Profile Engine

The horizontal alignment of the engine naturally creates more balance within the vehicle.  The horizontal engine design is symmetrical, placing half the engine weight on each side of the vehicle.  The symmetrical design is also flatter so that the weight of the engine sits lower in the vehicle, thereby lowering the center of gravity.  The lower than average center of gravity does not anchor the car to one side or the other thereby increasing efficiency.  It also provides the driver with quick, balanced responses.