What is a Boxer engine? Well, if you have asked yourself this question, don’t worry, you are not alone on this one. The Boxer engine is basically another engine configuration available in the automotive world. You have your V-shaped engines, inline engines and flat engines in this case. By the way, there are plenty of articles that explain this engine in depth. So, I am not going to reinvent the wheel here but try to share information and point you in their direction for more details.
How is it different?
It is different, again, by the way it is configured. Instead of having the pistons evenly tilted creating a V-shape, or one behind the other, vertically, in a straight line, the pistons on the “flat” engine oppose each other. These engines can be positioned lower within the car. The weight can be more evenly distributed and due to its opposing forces, it might vibrate less.
The flatness of this engine allows it to have a more direct transfer of power to the transmission, which makes the power transfer more efficient. According to SportSubaru.com’s article Subaru Boxer Engine Explained, “Subarus are the most fuel efficient AWD vehicles in America, often getting better gas mileage than its FWD competitors.” In this same article, they mention the safety advantage of the Boxer engine. In case of an accident the engine drops instead of going into the cabin.
How it works?
This engine works just like every other internal combustion engine would. The difference is the geometry of how the pistons and cylinders are placed in relation to each other. The pistons do not share cylinders but are offset. The position of the pistons, like mentioned before, can be a benefit. But it can also come with its negatives. Since the cylinder sleeves, for the two sets of pistons, point in two different directions, the Boxer engine needs two sets of cams, intake and exhaust manifolds. This translates to more parts. More parts means that more things can break.
The Boxer engine might seat low, and this might be good for safety, center of gravity, spacing on top of the engine, etc. But this also brings a drawback on the serviceability of the engine. The width and tightness of the engine in the car might make it hard to access parts that need service, at home at least. Service for this engine might require more time taking it to the pros, rather than doing it at home.
Just to reiterate, not everything on the engine is negative. The size of the engine and its flatness helps where it seats within the vehicle. The geometry of the engine produces less vibrations and it makes the power transfer more efficient. It is safer in case of accidents and it lays in a more symmetrical way inside the car.
Resources
One of the main resources that can help you understand this engine better, should be an article written by The Drive. You can access The Drive’s article here. The article was written in 2020. It has FAQs, positives, negatives, history, you name it. This is one of most complete and thorough written articles I have found. It is definitely worth the read.
A quick resource you can also refer to, if you don’t have too much time to read, is this rather biased video (it is from Subaru) that gives a visual explanation to everything I have mentioned above. I am not a huge fan of the narrator’s style but it does the job explaining the good stuff:
I will be the first one to admit that this previous video was a tad bland and it can lose you at the beginning. It is not as technical but it has nice illustrations and it is somehow straight to the point. Now, there is way more details involved here. The physics and movements of each component of the engine needs to be taken into account when designing an engine, accessibility for serviceability, etc. If you want to taste some of these details, I will leave you with Engineering Explained video of a comparison of an inline 4 with a Boxer engine. It will not satisfy all your needs but it will definitely give a further explanation than just the overview from above:
Finally, just like the article on The Drive, the most thorough video that I saw, combined with a narrator style that resembles your dad and Conan, is this Donut Media video listed next. Donut Media, I can recognize that has been putting very useful material out there, while still making it entertaining with a very substantial sprinkles of dad jokes. Again, very useful and entertaining video, very much recommended:
This is a topic I have been wanting to look into for a while now. I hope this is useful to anybody out there that is trying to understand the Boxer engine a little better, either just for curiosity, understand something they are trying to purchase or understand something they already own. Again, hoping that this was useful to you, we will meet again on the next one.
DL