Impreza versus Forester

[2KWIK4U]

Do any of you Subaru experts know if the Forester was built on the Impreza platform? The Subaru build book I have says they are the same so if I get a Forester 04-07 it could be used as my donor, right?

Thanks

[PhyrraM]

The Forester IS an Impreza, albeit a tall one.

Almost everything will be the same with the exceptions of a few suspension bushings and taller struts. They are usually lower geared for the final drive to deal with the bigger tires.

Seats *may* be mounted higher, but I'm not sure. I have seen STI seats in a Forester and they didn't really look lower.

[2KWIK4U]

I was hoping so, although I knew about the final drive. I planned to change it when I went to a limited slip inner.

Thanks for the info

[vozproto]

On that note...
What are the differences between the Forester/Impreza and Forester XT/WRX?

Are we looking at a case of a missing turbo/intercooler?
Or is it more than that?
Injectors? Air intake? etc?

The WRXs get quite good resale out here in Colorado and if I can same some dough by getting N/A and adding an OEM or aftermarket turbo I'd love to have that option.

[2KWIK4U]

Acording to my performance book the Forester was always produced with the 2.5 engine. The Forester XT just has the turbo 2.5 I guess. Where the 2.5 was not avalabile in the Impreza WRX untill 06 I think, I will look up more when I get home from work.

If someone knows more feel free to tell me I am wrong

[Evan78]

02-05 WRX had a 2.0L turbo, 2006+ has 2.5L turbo. 2004+ Forester XT (FXT) is a 2.5L turbo. All non-turbo 4 cyl engines are 2.5L, unless you go back pretty far (before 2002 sometime).

I highly recommend reading Cars101.com for brief overviews of year to year changes. Start at the bottom of these pages and read up through the years. It won't answer all your questions, but worth a read.

http://www.cars101.com/forester.html
http://www.cars101.com/impreza.html

[PhyrraM]

Yes, in the modern era ('02+) ONLY '02-'05 WRXs had 2.0s. ALL other turbo Subarus were 2.5. Various tunes and slight format adjustments though.


edit....only applies to the North American market.

[Evan78]

The WRXs get quite good resale out here in Colorado and if I can same some dough by getting N/A and adding an OEM or aftermarket turbo I'd love to have that option.

I wouldn't recommend trying to save money by getting a non-turbo model and adding a turbo to it. I'm not very familiar with the n/a engines, but I doubt that the savings are big enough to make it worth it. With a non-turbo model the items that come to mind are a weaker bottom end, different heads, no turbo provisions in the ECU. I'm not sure if the manifolds are interchangeable or not.

[Twinspool]

Cam profile, CC volume, compression ratio, gasket types, fuel injector size... it goes on and on. For a complete engine build are the 2.5 cores (semi closed deck) interchangeable?

[DrieStone]

I thought 02-05 WRX were 2.2 not 2.0

[Brian Apple]

Non turbo forester block and heads are not the same as the turbo model. ECU and harness are obviously different also. No savings if you plan to have a turbo car. But you could build a 200 hp car NA if you choose to.

[BrandonDrums]

I thought 02-05 WRX were 2.2 not 2.0

Nope, 02-05 were 2.0 (EJ207). A popular engine build more or less is to increase stroke on an EJ20 up to 2.1-2.3L or De-stroke a EJ257 (2.5L) to 2.2-2.3. The 2.0L has room for more stroke and has good heads for low-end flow. The 2.5L is over-square meaning it has a long stroke nearly or exactly equal to the bore which puts the rods at higher than optimal angles thus pushing the pistons a bit hard on the cylindar walls, it's one of a few reasons so many subie's eat pistons/ring lands. De-stroking the 2.5 eases that issue and provides a much stronger engine with more power at the top-end. Perhaps that's where you got the idea where 02-05s were 2.2L

Fun fact: The Forrester XT for about a year and a half was the fastest and most powerful production vehicle Subaru sold in the US. The STI wasn't brought here until 04 (as an 04 model, I think they went on sale mid-way through 04) so I think it was sometime in 02 through Q2 or so in 04 that the Forrester XT ruled the speed game for Subie. Crazy. It has AVCS and everything, most Forrester XT owners have no idea they are essentially driving a 5 speed STI around.

I'm considering sourcing a wrecked Forrester XT as my donor, they are less likely to be molested by the previous owner aside from the wreck that gets them a salvage title. In theory, the only donor bit from the Forrester that might not work on the 818 is rear lateral links (one of the main 'links' in the multi-link setup). That is just a solid rod that essentially sets the fixed camber angle of the rear wheels. Since the forrester sits higher, dropping the ride height as much as an 818 likely will would make the Forrester's lateral links way too long giving the rears too much negative camber. Easy fix though, serious STI and WRX guys often swap in adjustable lateral links. You can also just get lateral links off a junked N/A impreza if need be for way cheap.

I'm just going to wait until more details about the chassis are released though. I think most 818 buyers should hold off from buying donors as well until then for the same reason, could be FFR provides some key bits that open up the donor list to Legacies, outbacks etc. which also have 2.5L turbo versions virtually identical to the 06+ WRX's.

Besides, there will be more wrecked 06/07 wrx's by then which come with some pretty sweet brakes lol.

[PhyrraM]

Turbo Forester (in North America) was a '04 model year introduction, the same as the STI (and the Baja Turbo too). I have no idea which actually hit the dealer lots first. Imprezas and Foresters come from Japan, while the Baja is assembled here alongside the Legacy in Indiana.

Legacy turbo was introduced with the new generation redesign for the 2005 model year.

[Evan78]

02-05 were 2.0 (EJ207).

Probably a typo, but the EJ207 has never been sold in the US. 2.0 WRX motors were EJ205's.

Fun fact: The Forrester XT for about a year and a half was the fastest and most powerful production vehicle Subaru sold in the US. The STI wasn't brought here until 04 (as an 04 model, I think they went on sale mid-way through 04) so I think it was sometime in 02 through Q2 or so in 04 that the Forrester XT ruled the speed game for Subie. Crazy. It has AVCS and everything, most Forrester XT owners have no idea they are essentially driving a 5 speed STI around.

The Forester XT wasn't introduced until the 2004 model year. They still had the small TD04 turbo that WRX's used from 2002 to 2007(?) so they didn't develop nearly as much power as an STi. I'm sure you're aware of this, but where there's a lot of people new to Subaru's, I thought clarification would be helpful so someone doesn't get the wrong idea.

[2KWIK4U]

The Forester XT wasn't introduced until the 2004 model year. They still had the small TD04 turbo that WRX's used from 2002 to 2007(?) so they didn't develop nearly as much power as an STi. I'm sure you're aware of this, but where there's a lot of people new to Subaru's, I thought clarification would be helpful so someone doesn't get the wrong idea.

If I understand correctly you can upgrade the Forester XT to STI power levels pretty reasonably, right?

[Evan78]

Reasonably, yes. Change the turbo to the STi turbo and change injectors (I'm assuming Forester's are smaller), possibly fuel pump. STi probably has a different intercooler.

[PhyrraM]

Reasonably, yes. Change the turbo to the STi turbo and change injectors (I'm assuming Forester's are smaller), possibly fuel pump. STi probably has a different intercooler.

Correct on all counts. Add camshafts and intake ports (minor changes), slight compression ratio difference (only later years), and the ECU tune -- and that pretty much covers it.

[BrandonDrums]

Probably a typo, but the EJ207 has never been sold in the US. 2.0 WRX motors were EJ205's.

The Forester XT wasn't introduced until the 2004 model year. They still had the small TD04 turbo that WRX's used from 2002 to 2007(?) so they didn't develop nearly as much power as an STi. I'm sure you're aware of this, but where there's a lot of people new to Subaru's, I thought clarification would be helpful so someone doesn't get the wrong idea.

Not a typo, I was just wrong :-P thanks for setting me straight. As for my wrongness about the Forrester, the mechanic that built my engine who's got a bad-a STI swapped 07 Forester XT (who has a fairly thick Czech accent) told me about the Forester being, at least for a short period of time the fastest subaru sold in the US. Perhaps there was a lag between the 03 and 04 WRX being on lots along with the delay in the first STI coming to town. He definitely said the Forester for a time was the fastest turbocharged model for a short period but obviously I don't know what that period of time is.

I guess that's a fun fact that isn't that fun because I don't know the details correctly. I'll have to find out the specifics and get back to you.

B

[Evan78]

Here's how it went by my memory for turbo Subaru models:

2002-03 WRX 2.0L
2004 introduced Forester XT 2.5L, STi 2.5L
2005 introduced Legacy GT 2.5L
2006 changed WRX to 2.5L

I didn't include Outback, Baja, Tribeca because I don't know them off the top of my head.

[PhyrraM]

I didn't include Outback, Baja, Tribeca because I don't know them off the top of my head.

Baja 2004 for the Turbo. Outback is the same as the Legacy, so 2005. Tribeca has always had a 3.0 or 3.6 H6.

[2KWIK4U]

Thank's for the info, now I just wait to see what the final design will be!

[ironman16nc]

I'll be watching and waiting for the full details too. I have a 2005 Baja Turbo (which, yes, is 2.5L and built on the Outback frame). Although I LOVE my Baja for doing everything and anything, turning it into a F5 when it's Baja life ends would be a very sweet exchange!

[fateo66]

Correct on all counts. Add camshafts and intake ports (minor changes), slight compression ratio difference (only later years), and the ECU tune -- and that pretty much covers it.

Actually FXT, and LGT's both share STI cam shafts and side feed injectors.

[2KWIK4U]

Actually FXT, and LGT's both share STI cam shafts and side feed injectors.

That's good to hear

[Street Rate Parts]

Hey dont forget that there is some differences in the width of the actual a arms and rear end pieces. The Forester has 1cm narrower A arms than the STi and .5cm narrower than the WRX. I ran into this issue at a rally a bunch of years back

[projectrally]

The Forester XT (and 05+ LGTs) with the 5MT have the the stronger version of the 5MT, too. I'm pretty sure that the FXT had a 4.44 final drive where the WRX has a 4.1, so the gearing would be a bit more aggressive.

Then again, I could be really wrong. I was a hardcore Subaru nerd for a while a few years ago (among the handful of Subarus I owned were an 04FXT and the 05 LGT Wagon with the 5MT). But I really quit paying attention to the highly technical details and engine codes about the time I sold my LGT in late 2007. I've forgotten so much that I'm a pretty unreliable source of info these days.

[flynntuna]

Every time I'm driving my forester, I wonder how long I can resist the urge to turn it int a 818 lol.

[Samiam1017]

Ok I don't want to jack a thread so maybe some of the experts can start a new one. But since the book was open here I might as well ask. How about a thread that list the engines and hp/torque specs. And maybe the goods/bads of each? Somebody also mentioned final drive ratios. How about adding the usable trans with the gear/final drive ratios. I know it's a lot of work but it seems a few of the experts know all this already. Thx

[bromikl]

Darn it. I wish I had a place to park it until I get my kit. Maybe someone here wants it. According to this thread, it's (mechanically) an STI.

http://milwaukee.craigslist.org/cto/3262998121.html

[JRach]

Correct And the early XT's actually have the same head castings as the STI. Even some later models (when the compression was bumped up just a little bit) still shared the head design, but the compression increase was due to slightly different head gasket thicknesses.

As for parts you'll actually use for the 818 (as far as i've read from the 818 parts list), the forester will supply everything you should need. The slight difference in rear lower link lengths can be adjusted at the knuckle with a camber bolt, same goes for the front control arms. Brakes/hubs/knuckle assemblies are essentially the same design (minus the nice 06/07 wrx brakes and aluminum control arms).

The only things they changed in the Forester XT to bump up the ride height was a taller rear strut, different springs and a spacer between the frame rails and front crossmember.

Lastly, some may prefer the 4.44:1 gear ratio found in the XT vs the 3.9:1 in the 02-05 wrx.