How does a boxer engine work?

How does a boxer engine work? You’ve surely wondered about this more than once, and the way this type of engine works is somewhat different from the rest. Before we get into the details, it’s essential to know: what is a boxer engine?

A boxer is an internal combustion engine whose pistons are arranged horizontally rather than vertically, as we are used to. It works horizontally, which is why it can be described as a flat engine. The reason? Its cylinders are arranged in two banks, one on each side of the crankshaft.

Engines that share a single crankshaft are called 90º engines, while those with one crankshaft per bank of pistons are called 180º engines. It’s important to note that this type of engine should not be confused with so-called ‘opposed-cylinder engines’.

Karl Benz, a German engineer, managed to patent his first horizontal internal combustion boxer engine in 1896.

What makes boxer engines special?

Besides having a reputation for complexity, it’s worth highlighting that they are flat engines that are considerably shorter than their conventional ‘V’ counterparts. They have a lower centre of gravity, which can translate into improved stability, helping to avoid the ‘pitching’ that a conventional engine can produce.

This extra balance in boxer engines is due to the fact that each piston’s stroke is counteracted by the same movement of the piston on the opposite side, unlike conventional engines designed in a ‘V’.

Another characteristic of boxer engines is their sound; just think of the Subaru Impreza to get an idea. This distinctive sound comes from the lack of covering over the engine’s other components, compared with a conventional engine. Combined with its position ahead of the rear axle, this results in a vehicle with more neutral handling and a much lower centre of gravity.

Besides some advantages, they also have drawbacks, such as price. These engines are somewhat more expensive, since you have to think about ‘doubling’ the investment cost, as they have two cylinder heads, one for each row of cylinders. Manufacturers also have to invest in what are called ‘balancers’ to prevent possible vibrations. As for maintenance, experts say their lubrication is somewhat more expensive, since better oils must be used.

Many cars have gone down in automotive history for fitting a boxer engine; perhaps the most famous are some Subaru or the Porsche, but brands such as Citroën, Volkswagen, Lancia and Ferrari have also fitted them to some of their most iconic models. Some sources say that this type of engine acquired the name ‘boxer’ from the horizontal movement of its pistons, which can resemble the movements boxers make in the ring.

https://www.youtube.com/watch?v=Dj-7U9A3B-w