• Sep 23, 2010
Subaru's Third-Generation Boxer Engine – Click above for high-res image

Boxer lovers, the next chapter in your love affair has just begun. Fuji Heavy Industries, parent company of Subaru, has introduced the latest, third-generation boxer engine that will relieve the second-gen after 21 years of service. This is a brand new lump, not a rework, and FHI has built a factory just to produce it.

The bore and stroke have been increased, and it will be available with four cylinders in 2.0- and 2.5-liter displacements. The intake ports have been redesigned, lighter pistons and connecting rods offer reduced internal friction, and separate cooling circuitry for the block and the head are some of the changes that have resulted in a lower emissions and a ten percent increase in fuel efficiency. No power figures are being quoted yet, so we'll have to see how it measures up when it finds its way into production engine bays.

This new boxer will be Subaru's primary engine, and will first be seen in the Forester. Follow the jump for the press release, and you can have a closer look at it the high-res image below.


[Source: Subaru]
Show full PR text
FHI Develops a New-generation Subaru Boxer Engine
New Horizontally-Opposed engine, providing superior combination of environmental friendliness and enjoyable drivi
ng

Tokyo, September 23, 2010 - Fuji Heavy Industries Ltd. (FHI) has developed its new-generation boxer engine* that combines the technology and know-how used in Horizontally-Opposed Boxer engines, the core technology that has supported Subaru's unique driving since it was first employed in the Subaru 1000 in 1966. This overall renewal is the first in 21 years, since the second generation boxer engine was introduced in the first Legacy models in 1989.

This new-generation Horizontally-Opposed 4 cylinder gasoline engine, the third generation Subaru boxer engine, showcases Subaru's latest engineering research and development. It offers a new performance level by further refining Subaru's unique expertise in Boxer engine technology. The engine was entirely renewed, starting from the basic structure, while all the advantages of the horizontally-opposed layout were maintained: lightweight, compact, low center of gravity, and superior vibration balance. New-generation improvements include advances in both environmental friendliness, such as an approximately 10% improvement in fuel efficiency, and driving performance for smooth acceleration in all speed ranges. Furthermore, FHI designed the new engine with consideration of the technology's expandability and potential capability to receive further upgrades meeting future environmental measures.

FHI built a new factory at the Gunma Oizumi Plant exclusively for the production of this new-generation boxer engine. This new plant offers state-of-the-art production facilities that make full use of FHI's engine manufacturing know-how developed to date, as well as a highly efficient production system delivering products meeting the highest quality standards.

Major Features of the New-generation Subaru Boxer engine
The overall structure of this engine has been totally renewed, by reviewing the bore and stroke for the basic structure to
allow a longer stroke than current engines. It is designed to achieve high efficiency in basic performance, allowing the
smooth and sporty rotational properties for which Horizontally-Opposed engines are known, while also making improvements in practical torque and environmental friendliness. This engine is available with 2,500 cc or 2,000 cc displacement, both with 4 cylinders. These models will now be positioned as our main engines.

The New-generation Subaru Boxer engine
・ The bore and stroke, the basic structure of this engine, have been reviewed to achieve a compact combustion chamber as well as a long stroke, which was difficult previously due to chassis mounting conditions in boxer gasoline engines. This allows high combustion efficiency, and generates a sufficient mid-low speed torque with improved fuel efficiency and practicality.
・ Improved fuel efficiency has been achieved through optimization of intake port configuration and the addition of partitions inside ports, the use of TGV (Tumble Generated Valve), and the use of an EGR (Exhaust Gas Recirculation) cooler.
・ AVCS (Active Valve Control System) is used on both intake and exhaust valves. For the intake side in particular, an intermediate lock system allows valve timing to be advanced or delayed for precise control over intake and exhaust valve timing, allowing maximum engine performance in output, fuel efficiency, and exhaust emission.
・ The use of lightweight primary moving parts, such as pistons and connecting rods, and a highly efficient and compact oil pump provides an approximately 30% reduction in friction loss and improves fuel efficiency and revolution response.
・ Cooling has been optimized by using separate engine cooling circuitry for the block and the head, resulting in improvements in fuel efficiency and output characteristics.

FHI is fully committed to develop new products on the theme of integrating enjoyable and reliable driving with environmentally friendly solutions. This same theme applies to this new-generation boxer engine, which will be
positioned as a main engine and the starting point of its future power unit strategy. Starting with the Forester, the new engine will be deployed in other Subaru products in the future.
* Boxer engine: Also known as a Horizontally-Opposed engine. In this design, the pistons are arranged symmetrically left and right along the crankshaft. When the pistons move, they resemble the punches thrown by boxers, thus resulting in this popular name.


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    • 1 Second Ago
  • 85 Comments
      • 4 Years Ago
      Dear Subaru: Please let the first STI with this new engine make at least 330hp. And fix the gear ratios or let it rev higher so we can reach 60 in 2nd. The WRX should not be faster to 60 than a car costing 7k more, DCCD be damned.

      Do that, and I will buy one.
        • 4 Years Ago
        the wrx is not only faster to 60, its simply faster

        even around a racetrack

        the sti is for looks
        • 4 Years Ago
        Agreed. I've driven the WRX and aside from the fact that the shifter sucks and refuses to get in gear many times, the trans is very good. Never actually driven an STI so I guess I can't truly comment on it's trans.
        • 4 Years Ago
        The original US version WRX had a long second gear to give impressive 0-60 times. It was by far the worst part of that car and made shifting up sequentially totally choppy. It did not have a smooth timing from 1-2-3 because 2 was so long shifting in or out of it required a different pause. Hated that. The legacy 5 speed in the current WRX is just right.

        As you may know Subaru isn't about dragging. The diffs and brakes alone make the STI way more potent. The six speed STI tranny is also very well known for it's strength.
      • 4 Years Ago
      Consolidation. This is why Subaru makes predictably good cars. They make a good design. They stick with it for a long time, in this case 21 years, making incremental changes along the way. They take one engine design and tweek it or add to it for different uses across their entire lineup. Basic car architecture, suspension and transmission technologies also carry over to every product they make. The Tribeca is their least conformant product, at least offered in the US, but even its H6 is the same basic design as the H4. They don't make drastic redesign.

      Subaru has been a master at consolidation for a long time. All car companies seem to be learning that they must more closely follow the path of consolidation, not just in functional design, but in their marques, sales structure, option packages, etc.
      • 4 Years Ago
      -> I wonder whats the name of this engine?

      1st Gen = EA (currently own a EA82-FI, an '89 GL Touring wagon)
      2nd Gen = EJ (used to own a EJ20, an '04 WRX wagon & EJ25, an '06 WRX wagon)
      3rd Gen = ??

      -> I'm a fan of Subie's Boxer engines, so quirky and unique for its own good. Just add a real nice CAT-Back exhaust and it will be music. Sure Subie nowadays has becoming infected by the TBS (Toyota's Beige Syndrome), the last cool Subies are '07s and below.

      -> I'm also a fan of Honda B, K, C30/32, and F20/22C engines. As I currently enjoy my F22C on my S2000. Honda is untouchable when it becomes to N/A I-4 engines.
      • 4 Years Ago
      The article says both the bore and stroke have been increased, now im no expert but shouldn't the displacement also increase if this were the case?
      • 4 Years Ago
      Sexy. I'm assuming power output will be equal to, or better, than the 2nd Gen's so this seems made of win :D
        • 4 Years Ago
        Quick assumption here:

        Says it's replacing a 21 year old engine.

        Also says a 10% increase in fuel efficiency.

        Just doesn't seem too great of an increase. I know their current engines are nice, but seriously.. the old engine was built on 21 year old technology.

        Bring the boxer diesel!! Come on Suburu. I would love a $25,000 200hp / 300 torque Boxer engined Subbie! 31mpg city and like 40 hwy. I know it would cost more than that.. but a guy can dream!
        • 4 Years Ago
        Nice, and about time.

        Presumably, there will be a new-gen Porsche engine coming out soon as well, given that Porsche and Subie co-develop boxer. I wonder how that'll be.
        • 4 Years Ago
        30% less internal friction

        wow
        • 4 Years Ago
        Hazdaz. Seeing how most of the DI engines out right now are having severe carbon build-up problem, I'm glad they didn't go that route. Of course if and when manufacturers figure out how to minimize that problem or keep it to the same level as the current PFI engines, DI would be a good tech to have on the (Subby) engine.
        • 4 Years Ago
        and economy should be up to boot, win win.
        • 4 Years Ago
        Very interested in seeing what this engine can do, but disappointed that no talk of DI. Of course DI could be something that is added after the fact (especially if they kept it in mind), but for a brand new engine, it's disappointing to not see it from day-one.
        • 4 Years Ago
        Mike: just because the old engine architecture was 21 years old doesn't mean it was still running the same parts as 21 years ago. A lot of the efficiency tricks are in the intake/head/exhaust, all of which can be revised without making a "new" engine. I'll bet over 21 years things have changed to help out. After all, they are making a few more hp than in 1989. ;)
        • 4 Years Ago
        I can't wait to see how they managed to increase bore and stroke yet maintained the same displacements.
        • 4 Years Ago
        @ Hazdaz

        Subaru already showed off a direct-injected boxer engine in the Subaru Tourer Concept. They also showed it, via Toyota, in the FT86.

        DI isn't difficult to adapt to any engine, however it adds a significant cost. I'm sure that in this engine there will both be MPI and DI versions. Lower-end models will likely stick with MPI and higher-end will get DI.
      • 4 Years Ago
      Timing chains please!

      only question is will these blocks keep the current EJ style transmission bolt pattern?

      • 4 Years Ago
      yea, clearly the honda 4 cylinder turbo has been met with great praise. lets be honest, it aint no B16
      • 4 Years Ago
      Heh... you have difficulty in clearly expressing yourself. I think you meant to say "Crosstour is tough to look at."
      • 4 Years Ago
      "New-generation improvements include advances in both environmental friendliness, such as an approximately 10% improvement in fuel efficiency, and driving performance for smooth acceleration in all speed ranges"

      Better torque curve?
      • 4 Years Ago
      Actually, if you look at the sales for the past 1.5 years, when every car maker was selling significantly less than the previous year (30%-50% on average), Subaru was selling MORE. Subaru's are very popular in areas that are mountainous, have adverse weather, or an outdoorsy crowd. If you go to Colorado, very high percentage of Subarus. Same with the northwest (Washington state) and northeast (Maine). Maybe a bit surprising, but maybe not, tons of Subarus in the LA area. Probably due to the abundence of outdoor activities within a 2-hour drive. On my sister's street in Irvine, out of the ten houses, five have a Subaru parked in front.
      • 4 Years Ago
      In glancing over the specs, it appears that this new engine will more easily be adjustable electronically for different styles of driving, among other things?

      Any of the nerds out there better able to explain some of that press release info?
        • 4 Years Ago
        It's marketing fancy speak for electronic VVT.
      • 4 Years Ago
      Fanboys suck.
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