Originally invented and patented by Karl Benz in 1896, it was the very first internal combustion engine. He called it the ‘Contra engine’, as the horizontal pistons worked in such a way as to cancel out the action of the opposing piston. Regardless of the number of cylinders, anything from two to 12, the boxer engine doesn’t need counter weights or a balance shaft.
The pistons that are across from each other move toward the crank and away from the crank at the same time. This gives smoother operation and a crankshaft that is lighter because no counter balance weights are required. It also reduces vibration. Another advantage is that because the engine is wide and short it lowers the vehicle’s centre of gravity. This reduces body roll and improves handling.
The engines are wider when compared to an inline four or a V6, something that you discover when you first attempt to change the spark plugs on a Subaru. Working around such a tightly packaged engine bay is the frustration of many mechanics. Most companies prefer engines that are easier to work on and they, therefore, avoid boxer engines. The major companies using the boxer layout are Porsche in their 911 sports cars and Subaru across the range.
The Lykan Hypersort, which made an appearance in the Fast and Furious 7 film, uses a Porsche derived, but heavily modified flat six engine. The engines are also more complex than conventional setups as the cylinder block is split into two halves. This requires the use of two complex items instead of just one. They are also much noisier than conventional engine layouts, something local Subaru enthusiasts exploit by replacing the exhaust mufflers to amplify the boxer rumble.