Subaru Reveals More Efficient Third-Gen Boxer Engine

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Subaru Reveals More Efficient Third-Gen Boxer Engine

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Subaru Reveals More Efficient Third-Gen Boxer Engine

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The current, second-generation Subaru boxer four-cylinder engine has been in production for over two decades, so needless to say a replacement has been a long time coming. And now it’s here, with Subaru completely redesigning its staple powerplant to help the company move forward in an increasingly fuel-efficiency-focused world.

Available in both a 2.o-liter and 2.5-liter displacement, at first it seems there’s little new with this four-cylinder engine, but it’s the details that matter most. With a new bore and stroke, the porting has been redesigned, while the pistons are lighter and the con rods help reduce internal friction. Also included is Subaru’s AVCS (Active Valve Control System) variable valve timing system. Subaru claims these advances have resulted in a 10 percent improvement in fuel economy.

Another benefit of the new design are separate cooling ducts for the block and heads.

No performance numbers have been released but Subaru claims the new design makes for advances in driving performance with, “acceleration in all speed ranges” while stating that the new engine has been designed to work with advancing technology – likely meaning it’s capable of featuring a direct-injection system, as well as adaptable to a hybrid setup.

The new generation boxer 4-cylinder will debut in the Forester and will then go on to replace the 4-cylinder boxer powerplants in the rest of the Subaru lineup.

Official release after the jump:

FHI Develops a New-generation Subaru Boxer Engine
New Horizontally-Opposed engine, providing superior combination of environmental friendliness and enjoyable driving


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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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by complacent »

I'm really interested to see more on these motors. It's been a while since they've spit out a completely new motor.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

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:popcorn:
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Raven »

These should be hitting right around when I want a new car in a year or so.
All my cars have drum brakes and are sub 200 hp, what am I doing with my life?
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

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wait. so, I can get 26mpg instead of 24mpg on a four cylinder now?? Good thing the competition isn't well into the 30+ range these days b/c then Subaru would be in trouble.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Raven »

I wonder if they've fixed the dog-leg exhaust port with this?
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by complacent »

PGT wrote:wait. so, I can get 26mpg instead of 24mpg on a four cylinder now?? Good thing the competition isn't well into the 30+ range these days b/c then Subaru would be in trouble.
:poke:

weenur.

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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by PGT »

:lol:

seriously though.....one would think they'd be trying to leapfrog the competition vs. catching up to five years ago with their latest architecture.

adding 10% fuel economy on a product that already lagged behind the market in a major way is like throwing a deck chair off the Titanic
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by complacent »

fair enough. but in their defense, i don't see them catching up to the likes of the other import makers.

also, consider rated mileage for turbo-awd hondas... they're :censor: ing horrid!

given the awd, i think they're doing pretty darn good.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Raven »

Yes, AWD does suck the fuel.

And the regular WRX and Impreza really aren't that bad on fuel considering the size of the engine they use.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Sabre »

Yep, it's the price of awd... 28% drive train loss vs. 12-16.... Makes a big difference!

I REALLY want to see direct injection on these motors. So much more powA could be made!!!
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by zaxrex »

Yeah, direct injection as in diesel!
I'm sorry, but I have to call Shenanigans on this. WTF, first major re-design in the flat 4 engine?
Diesel 4 says what?
Maybe "new" for the US market, but the diesel Subarus here in the UK have me lusting after them. And that ain't no old engine...
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Mr Kleen »

the 2011 Forrester get's the new engine. for $200 you get a 1 MPG increase (with the auto) and a timing chain.
but if you order the turbo you get the old engine. :wtf:
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

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Mr Kleen wrote:the 2011 Forrester get's the new engine. for $200 you get a 1 MPG increase (with the auto) and a timing chain.
but if you order the turbo you get the old engine. :wtf:
:evil:
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Raven »

10% means the 30 mpg I could get on the highway will now be 33, which is pretty awesome. My friend used to get 30 mpg out of his 09 WRX and I know I can drive more efficiently than he does.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Mr Kleen »

The EPA rating for the new engine mated to the auto is 1 mpg better not 10% better.
The timing chain is nice if you plan on putting a lot of miles on the car.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

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Mr Kleen wrote:the 2011 Forrester get's the new engine. for $200 you get a 1 MPG increase (with the auto) and a timing chain.
but if you order the turbo you get the old engine. :wtf:
just want to note that I got 24mpg on my auto tranny V8 gas guzzler tax imposed luxo-barge
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Mr Kleen »

PGT wrote: just want to note that I got 24mpg on my auto tranny V8 gas guzzler tax imposed luxo-barge
yeah, but the price difference between the two would buy a LOT of gas. :lol:
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

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Mr Kleen wrote:
PGT wrote: just want to note that I got 24mpg on my auto tranny V8 gas guzzler tax imposed luxo-barge
yeah, but the price difference between the two would buy a LOT of gas. :lol:
one thing that didn't enter my purchase decision was fuel economy. heck, my STI was no better than the current car.

I guess it really comes down to direct injection at the end of the day, doesn't it? I wonder why Subaru didn't go this route with the redesign. perhaps the next iteration of the turbo motors will have it....after all the issues with the current ones, it would be smart on their part to have more precise control over fueling to manage the lean condition in one particular cylinder that causes the failures.
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Mr Kleen »

no doubt. my only concern with DI engines is how much head room will be left on the table? I love my 16G WRX but I had to upgrade the injectors and fuel pump to install it. with the pressures used in direct injection I just don't see the average shade tree mechanic being able to do any upgrades to the fuel system.

but I could be wrong. I'm old enough to remember how much the good old boys hated them new "cumputer cars" in the 1980s and look how good that turned out after a few decades. :wink:
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by PGT »

diesel fuel rails use as much pressure and they're swapped all the time to mod
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Re: Subaru Reveals More Efficient Third-Gen Boxer Engine

Post by Mr Kleen »

PGT wrote:diesel fuel rails use as much pressure and they're swapped all the time to mod
I just looked up the fuel pressure for the new Ford Ecoboost engines and it's only 2150 PSI. I read about one system that used fuel pressure that was much higher and I've been assuming they all were.
wow, I feel :screwy:
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