Why Does Subaru Use Boxer Engines?

Educational

Jul 09th, 2021

Why Does Subaru Use Boxer Engines?

Boxer engines use a non-conventional design and, thus, offer unique benefits because of it. While most automakers prefer the more regular or typical engine layouts, Subaru is possibly the only car maker using boxer engines in all models in its lineup, from the Subaru BRZ to the Subaru XV.

Subaru uses boxer engines because of the unique benefits these power units offer in terms of handling, performance, and safety. The atypical horizontal design of the boxer engine gives it a lower centre of gravity, enhancing the vehicle’s stability and balance. 

One drawback of a boxer engine is its width, which restricts airflow in the engine bay. It’s also more complex and more challenging to maintain and repair.

In this article, we’re going to explore everything there is to know about boxer engines. We’ll dive into their design, benefits, and their pros and cons as well. After this short read, you’ll understand why Subaru and some other brands prefer using boxer engines in many of the vehicles they produce.

Let’s get started.

What Is a Boxer Engine?

A boxer engine (aka flat or horizontal engine) is one that’s designed in such a way that the pistons move horizontally. That is significantly different from other engine types where the pistons are positioned to move vertically or in a V shape.

In a boxer engine, the crankshaft is located in the middle, while cylinders are placed on either side. This configuration earns the name 'boxer’, coined from the pistons' boxing-like, punching motion thrown toward the engine. 

What’s interesting is that the Subaru boxer engine, in particular, is found in each of the brand’s models. It offers unique benefits in all areas, from handling to performance and safety.

Even though Subaru is known for using the boxer engine in their vehicles, they’re not the only ones. Other carmakers like Porsche also use boxer engines in several of their models, while BMW is known for using boxer engines in their high-performance motorcycles.

Are Boxer Engines Any Good?

Whether they’re by Subaru or any other manufacturer, boxer engine cars enjoy a long list of benefits. As we pointed out in the last section, those benefits fall neatly into the handling, performance, and safety categories.

Here’s a sample of what those benefits are like.

Boxer engines improve handling

Remember: Boxer engines are flat with a centre crankshaft and pistons on either side. Pop the hood, and you’ll see that the engine lays horizontally inside the engine bay, which also means that it has a lower centre of gravity.

What does that mean for the car overall? First, the car is much more stable and balanced than engines with a vertical or v-shaped design.

Better stability and balance lead to much more improved handling overall.

Flat engines enhance a car’s performance

Boxer engines also improve the car’s performance, as the vehicle becomes much more stable, balanced, and responsive.

As mentioned before, a boxer engine is horizontal, with a centre crankshaft and cylinders on either side. But, more importantly, the pistons in those cylinders also punch outwards in opposite directions before punching inwards towards the crankshaft.

When that happens, the pistons cancel out each other’s inertia, resulting in an incredibly stable engine and produces fewer vibrations than other engine types.

Besides that, boxer engines are also smaller and lighter, resulting in better acceleration and fuel efficiency.

Horizontal or boxer engines are safer to car occupants during a crash

The unique design of boxer engines also offers the vehicle better safety. 

Suppose you were to get into a head-on collision in a car with a boxer engine. If that’s the case, then the engine’s low centre of gravity and horizontal design will cause it to fall underneath the car.

That’s much safer for the vehicle’s occupants because it means the engine will not be forced into the cabin instead.

What Are the Disadvantages of Boxer Engines?

The above benefits you get from boxer engines don’t come without tradeoffs. Two of their disadvantages are their shape and complexity.

Shape

We've mentioned several times already that the boxer engine is horizontal in shape. While that might offer plenty of benefits, the shape also causes problems in maintenance, repair, and airflow inside the engine bay.

Firstly, a mechanic is likely to have a more challenging time gaining access and reaching all the crucial parts of the boxer engine when performing maintenance or repairs. That’s going to be especially true if they aren’t experienced with boxer engines.

Even though the boxer engine isn't as high as in other configurations, it compensates with its width. However, that same width that adds to stability and all the good things said about flat engines restricts airflow inside the engine bay.

Restricted airflow might not be too much of a problem during regular driving. However, that’s not always the case since it can reduce engine performance if you’re driving at high speeds.

Complexity

Overall, boxer engines are much more complexly designed compared to inline or V-shaped engines. This is because all the necessary engine parts are squeezed into a broader, horizontally configured shape that distinguishes it from standard engines.

So, maintaining and repairing boxer engines does require specialised knowledge and skills that a regular neighbourhood mechanic might not have.

As many car owners already know, more complexity means higher prices for harder-to-get spare parts and specialist mechanics. You can search for auto professionals from our Australia-wide directory.

What Other Makes/Models Use a Boxer Engine?

Subaru isn’t the only car brand that’s known for using boxer engines in their vehicles. Besides them, Porsche and BMW also do have models that carry boxer engines.

You can find a Porsche boxer engine on models like:

  • Porsche 911
  • Porsche 718 Boxster
  • Porsche 718 Cayman

On the other hand, BMW is well known for using a BMW boxer engine in their motorcycles like the recent BMW R 1250 GS. Besides that, you’ll also find boxer engines on much older BMW car models like:

  • BMW 600 (four-seater microcar from the late 1950s)
  • BMW 700 (small rear-engine car from the late 1950s and early 1960s)

Find Subaru Car Parts and Engines Fast!

To learn more about boxer engines and other car parts, check out the blog at Carpart.com.au. There, you’ll discover plenty of educational car articles about vehicles from Australia and beyond! And if you’re looking for Subaru car parts, including Subaru boxer engines, you can check out these reliable Subaru auto parts wreckers in Australia. Or request parts via our Car Part Finder for quick results!


By Ray Hasbollah