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2012 Forester Auto
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4 Posts
Discussion Starter #1
New to the forums and Subaru's in general. I'm getting an XT Forester in the next few weeks and after a bit of poking around I'm wondering what the deal with the engine is. It looks like the 2011 XT's still had the EJ25, so is this the first year they've stuck the turbo on the FB25? After some poking around I've seen various chatter on Impreza forums about it being untested and owners being guinea pigs. I'd like to believe that Subaru has spent the past year testing it but regardless can tell me if I'm way off base or point me to any discussions about the FB25T?? Not even sure what notation they are using for it...

Thanks
 

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Premium Member
2014 Impreza Ltd CVT
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3,319 Posts
Cars101 still lists the EJ25 as the 2012 Turbo engine.

Keep us informed as Joe Spitz, who runs that site, is usually pretty good about it. Granted there have been mistakes there, but he is quick to clear them up.
 

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Premium Member
2008 Forester X Premium 5MT
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8,070 Posts
All turbos in the US are still on the EJ25 platform.

The FB25 is NA only as of now.
 

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2019 Crosstrek 2018 XT
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14,218 Posts
All turbos in the US are still on the EJ25 platform.

The FB25 is NA only as of now.
Subaru has painted themselves into a corner with 3 designs and neither the turbo or the NA is where they need to be...

EJ Turbo..needs a chain, FB previously Belt..improved with chain but still open deck design, eight valves and can't be turboed. Things don't seem to be well thought out.
 

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2015 Forester X 6MT 6-Gear Manual
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1,373 Posts
FB25 is 16V? I havent seen a block deck photo.
 

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2013 WRX Base 5-speed
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827 Posts
I'm willing to bet they will turbo future iterations in favor of dumping the 6-cylinders in face of the new federal fuel economy requirements. However I suspect the FB20 will be the first to get one.


(Pure speculation)
 

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10 XT 4EAT
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893 Posts
I believe I read somewhere that Subaru is indeed planning on turbocharging the FB engine, they are just waiting for a bit to see long term widespread quality of the FB.

I am also pretty sure that the FB is a semi-closed deck to try to fix the N/A headgasket issue.

And if you want to throw another option into the mix, there is the FA that is in the BRZ.
 

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2013 WRX Base 5-speed
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827 Posts
I Believe Toyota leaked rumors that they are working/testing a Supercharged Version of the FA for the new roadster...I don't see any reason Subaru won't try forced induction.
 

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2008 LL Bean (4EAT)
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4,785 Posts
... FB previously Belt..improved with chain but still open deck design, eight valves and can't be turbid...
The FB is still open deck, but the head design is completely changed. The head does not receive water from the block, but has its own coolant supply. So the head gasket no longer has coolant going through it from block to head. The head gasket is no longer such a thin ring of material perched on top of a thin cylinder top, easily stressed and damaged by movement of the unbraced cylinder tops.

Why can't the FB be turbocharged? I think Subaru will eventually do that.

I think Subaru developed the FB engine to extend the open deck block to all of its engines. The open deck allows economical die-casting of the cylinder blocks, with reusable steel dies. In a closed or semi-closed deck the cylinder block must be sand cast, where the sand mold is poured out and lost with each casting. Sand casting is slow and expensive. I think Subaru has tolerated this cost for the low percentage of turbo and diesel engines it makes, but eventually wants all of its engines to be die cast. The head design of the FB allows this.
 

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2011 Forester X auto
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841 Posts
Little off topic but....
Differences between open and closed deck?
Being a turbo v6 junkie for a long time, first time in a boxer engine
 

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2010 FXT 4EAT
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415 Posts
A two year old FXT with the turbo FJ engine might put me in the perfect timeline for my new (used) car! I am optimistic. Lets hope for 27-29 mpg's out of a turbo FXT.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,734 Posts
Subaru + Turbocharging = All things right with the world.

It'll be a cold day in hell if Subaru ever abandons that.
 

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2008 LL Bean (4EAT)
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4,785 Posts
More views of open and closed decks here:
Subaru Head Gasket Change. - Seattle Subaru Repair

This post also shows and explains the differences in deck design, and discusses the problem the open deck causes for head gaskets:
http://www.subaruforester.org/vbulletin/f88/2006-head-gaskets-problem-64464/index2.html#post716946

Here is a post about "pinning" an open deck to get the effect of a semi-closed deck, by using metal inserts to brace the cylinder tops:
http://www.subaruforester.org/vbulletin/f88/2006-head-gaskets-problem-64464/index8.html#post757022
 

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2008 LL Bean (4EAT)
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4,785 Posts
The FB engine continues to have the open deck with the free-standing unbraced cylinder barrels, but the water jacket around the cylinders does not continue up into the head. The top of the cylinder deck is capped by the solid bottom of a head having openings only for the combustion chambers. The FB head gasket is then more like a strong solid sheet than the EJ's lace doily with thin rings atop each cylinder barrel.
http://www.subaruforester.org/vbull...ilure-after-29k-91402/index2.html#post1003621
 

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2015 Forester X 6MT 6-Gear Manual
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1,373 Posts
Anybody source a FB block deck photo/drawing. Never seen one ( YET :)
 

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2015 Forester X 6MT 6-Gear Manual
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1,373 Posts
So how do we know what the FB deck looks like? - all I see here is EJ deck photos?
 
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