2017 Subaru Forester, 2017 Subaru Outback, 2017 Subaru Crosstrek
Denis Flierl's picture

3 Reasons Why Subaru Uses the Boxer Engine; Will It Continue?

Subaru celebrates 50 year of continually using the boxer engine. With plug-in hybrids and all-electrics coming, will it change?
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Subaru is the only automaker on the planet that uses the boxer engine in its entire lineup. They use it in the Forester, Outback, Crosstrek, Impreza, WRX/STI, Legacy and BRZ. Porsche is the only other automaker that uses the flat, H-shaped, opposed-piston “boxer” engine. It’s a good design and it’s winning awards. Subaru’s 2.0-liter turbo boxer WRX just picked up its second consecutive Wards 10 Best engines award.

The Boxer powerplant has been used by Subaru since 1966 and has been continually evolving. Subaru says that won’t change in the future. They will continue to use the engine to power their vehicles. There’s three reasons why Subaru is committed to the powerplant.

Acceleration is smoother in the boxer

V type engines which most automakers use, reciprocate the piston in the vertical direction, whereas in the horizontally opposed engine reciprocating pistons reciprocate horizontally. Because they cancel each other's power, there is less vibration and you can feel the smooth acceleration.

It lowers the vehicle’s center of gravity

Horizontally opposed engines have a lower overall height than general series and V type engines, due to the structure of the piston being horizontally arranged in the crankcase. It makes the engine lightweight, compact and it lowers the vehicle’s center of gravity. This makes for a more dynamic driving experience in Subaru’s taller all-wheel-drive vehicles that have a higher ride height like the Forester, Outback and Crosstrek. In Subaru’s performance WRX and WRX STI, the sports cars remain stable at high speeds in the corners.

Reduced damage during a collision

One of Subaru’s core values is safety, and boxer design helps reduce damage in a collision. Horizontally opposed engines are low in overall height, so the structure will be pushed under the floor in the event a frontal collision. Therefore, it’s difficult for the engine to be pushed into the cabin, reducing injury to the passengers. This is evident in Subaru’s high collision safety performance.

With new engine and powertrain technologies on the way, Subaru will continue to use the boxer engine in their Forester, Outback and Crosstrek all-wheel-drive vehicles, even in hybrid powertrain applications. With all-electric vehicles becoming more widely used, this could change that in a big way.

Photo credit: Subaru


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Comments

The boxer engine can at best be described as 'opposed cylinder' engine but not "opposed piston" engine. Piston that 'oppose' each other work in one cylinder head to head that, in it simples form, have two outside located crankshafts. A 'boxer' is not just a V-engine of 180 degree angle, but both piston move outward and inward at the same time. A boxer is unique achieving the advantages as described mostly by that feature. 'Opposing piston' engine are those of Achates Power, Pinnacle or OPOC, Regards
All three of those attributes are true. Now...compare the smoothness, lower center of gravity and crash safety to a Tesla Model S.
Fasteddie I like the Tesla, electric cars... and for the most part I agree with your statements but I have a hard time using the word SAFETY and Tesla in the same sentence. My opinion is based on the company and not the car but it is difficult to separate the two. Tesla is pushing technology out before it is ready and they are doing it for the wrong reasons. Their autonomous cars are one example. They are making the news as they are crashing into motorcycles and pedestrians because the sensors do not always recognize these as things the car should stop for.
Only time will tell if Tesla's push into more autonomous driving will be the right move. One thing I believe you and I would agree on is this: if cameras and computers had come before cars, humans would not be allowed to pilot a car! Our highways would be designed for autonomous guidance only.
That's the head of the nail and you hit it. The autonomous scene won't work till all vehicles are communicating and proactive on a larger scale, and the human element essentially removed along with it's inherent errors.
Which will probably never happen. Not this century anyway
autonomous is nuts. you need a real brain behind the wheel. get old and bad drivers off the road and problem solved. more public transit. smaller cars. less damn trucks. fewer ridiculous suvs...
Theoretically the boxer engine is really good but in real world i dont think it is. As an owner of one and having friends who have one too, the engine to me is a terrible design because it has been built to break. Blown engines ryme with subaru because of their terribke design which later bankrupt you from doing repairs
Could this be sour grapes
I've owned 3 Subaru's. 2 were rather new, I drove both to 125-150k each, and I had almost no problems with them (one had a wheel bearing issue, but that was it). The only one I had issues with was the SVX, it had a dismal transmission. But with 185k miles, the engine ran beautifully and had no issues.
I bought a 2002 WRX, had the dealer install a ton of upgrades like bigger turbo, injectors, fuel pump, up and down pipes and it dynoed at about 380 rwhp IIRC. Drove it 123,000 miles with zero problems, but was always careful on the maintenance. Traded it in in 2010 for an STi SE with just a reflash and it now has 137,000 miles. Zero problems. I have no idea how these cars came to be known as fragile or problematic. I think they are fantastic cars that handle like sports cars on 18" wheels and max performance summer tires, and like Sno-Cats in the winter with 17" wheels and Blizzaks. These are amazingly well made, parts don't break or fall off, and as long as you stick to a strict maintenance program are very reliable. The only thing I have ever replaced were brake pads and rotors. These were and are my daily drivers and never let me down. The awd system is superb, esp. on the STi with the switchable diff lock and I/.S and S+ modes. I will soon be getting another. With a few $$ in tuning they will stay with any Porsche except the turbo and will blow away most "sports cars". They really are that good. And lest you think I'm a WRX/STi nut, I have owned 5 Ferraris including 2 Challenge cars and raced them, a Shelby Brock Cobra Daytona Coupe, A Jaguar E type, 7 BMW's including 2 M3s and an M550i, various Mercedes, a Porsche 911 (993), 2 Corvettes, and just bought a Jaguar XJ220. And I still prefer the scoobies as daily drivers. And their seats are amazingly comfortable! Nothing can touch these cars in this price range. Sorry for the rant, but I have heard too many misinformed people tell me to watch my head gasket, etc. By far my favorite "go-to" car in bad weather, and we get a lot of snow upstate NY.
Unfortunately, you do not say why the Subaru engines blow and how frequent that is. I find that the boxer concept is a good one. If the engines fail it must have to do with detail.design or materials used. . BMW used the boxer in their star motorbike with good success. Access to the engine is likely difficult being buried underneath. I don't drive one so I don't know, How easy is it to make an oil change or chance the spark plugs?
Unfortunately, you do not say why the Subaru engines blow and how frequent that is. I find that the boxer concept is a good one. If the engines fail it must have to do with detail.design or materials used. . BMW used the boxer in their star motorbike with good success. Access to the engine is likely difficult being buried underneath. I don't drive one so I don't know, How easy is it to make an oil change or chance the spark plugs?
Interested in Foresters 2019 Trim of Touring and limited
We just bought the 2020 Forester Touring Trim, and we like it a lot. It is our first Subaru after owning Toyotas, Hondas, and VWs. The safety features and comfort are what sold us. There was not too much difference between 2019 and 2020, so I would see who gives you the best deal. I would have preferred to be able to purchase a more efficient E-boxer version that is being sold in Japan. Good luck to you. At the closing for our purchase, the dealer said; "welcome to the cult" truer words..
I purchased my 2006 Subaru Baja with 270,000 miles on it in 2013. It now has over 325,000 miles and runs strong. It recently began leaking oil at the cam seals but running strong. This is a work horse engine and hard to imagine one would down play the facts. Replacing the timing chain is a must as recommended by Subaru. Well worth the cost of less than 1200 dollars.
Subj: Buyers Remorse <rant> Buying a 2010 Subaru Forester X Premium was one of the WORST mistakes I have ever made with money. What a piece of crap. I bought into the JD Power "5-year Lowest Cost to Own," Consumer Reports most reliable vehicle, and IIHS safest vehicle b*****t. At 98,500 miles, I am now due for the following: Head Gasket and all engine seals replacement; Major Tune-Up: Timing Belt, idlers, water pump, thermostat, and radiator replacement; and major battery cleanup. The head gaskets are a known issue with Subaru H4 SOHC engines. The cost-cutting single-layer gasket is a HORRIBLE design that starts to leak between year 8 and 12. To repair this grotesque factory defect, one must REMOVE the entire engine from the vehicle for the major overhaul. You might as well go ahead and do a tune-up now too. $3600 Assuming the timing belt is in the same condition as the nearly shredded accessory belts ($100), the timing belt, creaky idler pulleys, hydraulic tensioner, water pump, and all associated seals now need to be replaced. $500 Also, because this is a Japanese vehicle approaching year 10, the plastic & aluminum radiator is expected to fail within the next year (extensive experience with JPN vehicles). This repair includes the radiator, upper and lower hoses, thermostat, coolant flush, and all associated seals. $500 The battery problems are due to a HORRIBLE design where the hood and quarter panels dump rain water directly onto the battery causing massive corrosion and general electrical issues (batt is 2 years old, but looks 8). $200 Note: Subaru is fully aware of how horrible their engine and head gasket designs are; thus, they ship the vehicles from the factory with STOP LEAK and conditioners already in the engine coolant. Compound this with the cost-cutting "idiot light" on the dash instead of a proper temperature gauge, overheating issues won't be discovered until it's TOO LATE. Checked your coolant recently? Neither had I until I did and found out that my reservoir was EMPTY--it all leaked out of the left head gasket. No temp gauge to tell me I was starting to have a problem. Perhaps the above listed ratings agencies should start to look into the 10-year cost to own being that the first 3 of 5 years is completely covered under warranty for all vehicles. From a previous comment: Sour grapes? OR Head-In-the-Sand? You decide. The prices listed above would be to pay a shop to do the work for you and assume they did it all right. Google: "Subaru replace head gasket" and see what you find. I'm amazed that there hasn't been a class action lawsuit against Subaru for the expanse of this issue (going on 20 years now). I'm in the middle of doing the repair myself. I'm in $3000 on parts, materials, and tools on a $7500 vehicle. A dealer offered $4000 on trade in, I declined (might be regretting that decision now). The H4 boxer engine is a nightmare to work on. The heads/valve covers are buried in the engine bay 1.5 inches from the frame rails. Apparently, all these years I've been spoiled doing *minor* repairs on older I4 Honda/Acura engines that are intelligently designed, compact, and EASY to work on. At 200k mi, their HG were never in need of repair, but had they been, it could've been done with the engine IN THE CAR. FWIW, I'm not your average shade tree mechanic. I'm an engineer working from the factory service manual. Anyways, hopefully this rant got you (the reader) to consider the *possibility* that the boxer engine is a HORRIBLE design and then go do some Googling about typical repairs and their costs associated with said engine/ manufacturer. Thank you for your patience in making it this far down. </rant> Joe
Joe ..... unfortunately your 2010 Forester falls within the problem date range. Much to Subaru’s credit, the carmaker replaced their OEM gaskets with SIX STAR MLS (Multi Layered Stainless) gaskets, which have solved the problem. On 2015 models and beyond, the number of head gasket issues in Subaru vehicles has been nearly nonexistent, and Subaru continues to be recognized as the auto manufacturer with more vehicles of 10 or more years still running reliably and virtually free from any major maintanance.
Thank you SO much for your honesty. Comfy high-up SUV’s with great visibility and traction in slippery situations. However, it was way too much of a hassle to deal with the constant attention of Subaru’s AWD-boxer scheme. I owned a 2014 DITurbo Forester XT touring for 9 months. For every month of ownership it spent a week in the shop. Before 50k miles the dealer discovered I had premature engine wear. Suspension parts were wearing out just driving on normal roads, no off-roading at all. Dealt with the “Christmas tree” effect with all the instrument cluster lights staying on a few times. “Limp mode” the local Subaru service dept called it. Engine problems, poor electrical system, and the interior rattles were absurd for a vehicle that young and one “built for adventure”. I got rid of it before the famous head gasket and wheel bearing issues came up when I decided to price a new CVT lineartronic transmission simulated 8speed in the XT models just out of curiosity....over $8k in parts alone. CVT’s are not serviceable, avoid them and especially the Subaru CVT’s. I went back to our family brand, Toyota, and I have been saving money ever since.
Thank you SO much for your honesty. Comfy high-up SUV’s with great visibility and traction in slippery situations. However, it was way too much of a hassle to deal with the constant attention of Subaru’s AWD-boxer scheme. I owned a 2014 DITurbo Forester XT touring for 9 months. For every month of ownership it spent a week in the shop. Before 50k miles the dealer discovered I had premature engine wear. Suspension parts were wearing out just driving on normal roads, no off-roading at all. Dealt with the “Christmas tree” effect with all the instrument cluster lights staying on a few times. “Limp mode” the local Subaru service dept called it. Engine problems, poor electrical system, and the interior rattles were absurd for a vehicle that young and one “built for adventure”. I got rid of it before the famous head gasket and wheel bearing issues came up when I decided to price a new CVT lineartronic transmission simulated 8speed in the XT models just out of curiosity....over $8k in parts alone. CVT’s are not serviceable, avoid them and especially the Subaru CVT’s. I went back to our family brand, Toyota, and I have been saving money ever since.
ok MR. ENGINEER...for starters there IS NOT a vehicle out there that lasts 10 years without calling for some form of overhaul of the powertrain. your precious honda crap requires a full timing overhaul to keep the warrantee at 120000 miles. if you skip this by 160000 miles the timing has thrown and you've either slammed a valve through a piston or stuffed a rod through the side of the block i.e. you're ending up paying $8500 bucks or so for a new engine. secondly it takes a half an hour to pull ANY of the boxer engines out of ANY Subaru body. the 100000 mile timing replacement with engine out takes less than 20 minutes and the kit for it costs 180 bucks. the manual calls for INSPECTION OF ENGINE SEALS and replacement as required. and finally its not the engine that has the issue its the standard HG that is the issue and that isn't always the case as my 2002 Subaru has 344896 miles on it and I've NEVER had to crack off a head or open the crankcase EVER. i'm just now considering changing my 2.5L engine as its just now starting to get piston blowby significant enough that I go through 1/2 a quart every 3 weeks to a month. so with that its obvious either you aren't a very good engineer or you're just whining cuz you got stupid and now you have to get your hands dirty. either way nut the hell up and be a man about it!!!!
My gt86 is now 7 years old and still runs like a new car (I drove it back to back with a brand new one I had on loan). Boxer engines went through a bad period when they made cars for the US market, like the 2.5s. Early and later engines are very good.