Subaru News: Rumorpile: End of the Line For Subaru's Six-Cylinder Engine?

[William Maley]

Subaru might be the next automaker to follow the downsizing trend. Speaking with Australian outlet CarAdvice.com.au, Yoichi Hori, Subaru's deputy general manager engineering department mentioned the possibility of dropping their six-cylinder engine - used in the Legacy and Outback models - and replacing it with a turbocharged four-cylinder.

“Our research said the six-cylinder model is decreasing in the world. So that’s why probably the future, many companies take the smaller displacement with a turbocharger, or diesel, or hybrid," said Hori.

As for a possible engine size, Hori mentioned that a 2.0L would be just right.

“In terms of the body size, a 2.0-litre with a turbocharger is enough, I think.”

Source: CarAdvice.com.au

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[Drew Dowdell]

It makes sense.  Most everyone can get 300 hp out of a 2.0T these days... GM was doing it 8 years ago.   GM has a 1.6T that can do 200 hp and 200 lb-ft of torque in Europe that will eventually make its way to the US, Ford's 1.6T makes 180 hp and 180 lb-ft, the 2.3T makes Northstar V8 like numbers but does so at a lower RPM. 

 

The main reason for wanting a V6 or I6 is for smoothness and refinement, but that doesn't really apply to an H-6 like Subaru's

[Z-06]

Logical, I see no need for the 6 pot engine from stand point of performance and cost effectiveness.

[Drew Dowdell]

The other thing I forgot to mention.  Subaru's 6-cylinder only puts out about 260 hp and 240 lb-ft of torque and it has a low take rate.   Almost any 2.0T can hit those numbers easily, so why should Subaru shoulder the cost of an extra engine line?  By offering a less expensive upgraded engine, Subaru can probably talk more people into paying for it while Subaru also gets lower development costs.

[regfootball]

they may still need a six for a three row

[Drew Dowdell]

Why? Every 3 row out there comes with a base engine with less than 300 hp, and except for the Durango, none have more than 360hp. A Turbo 2.0 and turbo 2.5 can cover that range.

[Cory Wolfe]

The problem with Subaru's six cylinder is nearly the same problem as every one else's; They haven't advanced technology wise. In 2005, Subaru offered three engines in the Legacy/Outback. A 2.5L NA H4, a 2.5L Turbo H4, and a 3.0L NA H6 were available. Let's just focus on the latter two.

 

The 2.5T was, at the time, rated for 250 hp & 250 lb ft of torque (this was later re-rated under SAE at 243 and 241). The 3.0 was rated for 250 hp & 219 lb ft of torque (also re-rated under SAE at 245 and 215). Assuming similar options, equipping the 3.0 adds an additional 50 lbs. Both engines required premium fuel. As you can see, there is really no benefit to choosing the H6 (later the H6 would prove as the more reliable choice, however). Now, let's jump forward 5 years to the next model with its revamped line-up of engines.

 

The 2.5T is now rated at 265 hp & 258 lb ft of torque. The 3.0 has now been bored out to 3.6 and is rated at 256 hp & 247 lb ft of torque. So what happened? Mechanically, the only notable advancement was a new asymmetrical connecting rod allowing them to increase the displacement. So, let's look at power per liter to see what's what. The old 3.0 had 81.6 hp/liter and 71.6 lb/ft/liter. The new 3.6 now has more at... Oh, wait, no... less, much less, at 71.1 hp/liter and 68.6 lb/ft/liter. All that work to increase bore & stroke for nothing. Okay, so what have they really pulled off here? Well, peak power is now available at 600 less RPM (but peak torque requires an extra 200 RPM), premium fuel is no longer required, and general NVH improvements have been made. This engine hasn't changed with the latest generation and is, in a word, underwhelming.

 

Subaru has a long history of offering turbo-charged H4 engines. Besides AWD, it is probably what they are known for most. While I haven't always agreed with replacing 6 cylinders with turbo 4's, in a Subaru, it just feels right. I loved every bit of my Subaru Legacy 2.5 GT with its turbo. I would love to see Subaru reinvest in a similar set-up.

Edited December 24, 2014 by blackviper8891

[Drew Dowdell]

great explanation BV. I am not in a position to look it up, are the Subaru 6es direct injection?

[G. David Felt]

It would be cool to know if the 6 cylinder got all the same advances as the Turbo 4's where it would sit in the HP/Torque.

[Cory Wolfe]

great explanation BV. I am not in a position to look it up, are the Subaru 6es direct injection?

 

Not 100% sure, but I think it's just port injection. I can't really seem to find it listed anywhere on Subaru's website. 

[vegito12]

I think a change has been needed, and may cost less in parts when going for repairs as sometimes these cars can cost more in parts than the auctual labour work that goes into fixing the car and should happen this year when the new cars get built with smaller engines and maybe just at 2 liter or just under would be good. The technology should be advanced and improved and made better with a 2litre no need to make it any higher than it is needed as in the article it is not as popular as it used to be as well. I know someone who owns a subaru think it is a 2.5 litre and has a big engine does consume petrol more when driving in town and going up the hill where he lives so a change is needed.

[818carfreak]

Subaru could really take a lesson from Porsche, I mean they have invested heavily into the opposed 6 and they have the knowledge. Subaru collaborates with toyota on the BRZ, why not Porsche? I'll tell ya why, subaru's target audience is looking for reliable awd cars that get decent gas mileage. Like some of you mentioned earlier, car companies are looking to downsize engine displacement.

[kestas57]

Still, I love the sound a six. Also, it is much smoother than any four pot I've ever been in. Despite this, with all the emissions rubbish going on I can't blame them for doing this.