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Old 08-29-2003, 02:01 AM   #1
atmosphere
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Default Forrester XT motor

Has anyone used this motor in a swap yet? Im looking to do a swap in the future for my GC8 and was wonder if this motor is a good option aside from the standard WRX 2.0 and if there are any problems associated with it. Thanks.
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Old 08-29-2003, 11:38 AM   #2
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it is very simmilar to the sti motor

it will eventually be a very popular swap but i don't know of any one who has doen it yet..

if you do it get the whole car as the ej255 has some new/odd differnces like throttel by wire
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Old 08-29-2003, 01:45 PM   #3
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AFAIK the only difference between the STi and XT long block is the cams. The STi has a longer durration and a little higher lift IIRC.

The STi also has a bigger i/c, bigger turbo and more boost.
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Old 08-29-2003, 04:15 PM   #4
atmosphere
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Quote:
Originally posted by Jaxx
it is very simmilar to the sti motor

it will eventually be a very popular swap but i don't know of any one who has doen it yet..

if you do it get the whole car as the ej255 has some new/odd differnces like throttel by wire
EJ255? Whats the extra 5 indicate or is it a typo? Also is it possible to retro fit a standard throttel, Ive heard that throttel by wire takes away "felling" in the gas pedal. Thanks.
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Old 08-29-2003, 04:25 PM   #5
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the ej255 = xt motor ej257 = sti motor

cams are the only difference... and yes you can change it from fly by wire BUT that would be crazy amount of work. You would have to rewire eveything with like a v7 harness and I dont know what the hell you would do for an ecu... would the v7 ecu work with the 2.5 block?
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Old 08-29-2003, 10:55 PM   #6
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the cams aren't the only difference... remember the sodium filled valves aren't part of the XT package. So the short block is identical and the heads have a few differences. That sums it up.

If your just looking to keep a 2.5 liter displacement why not get the STi short block bolt it up to RS heads and run that? Yeah a bit more technical but a whole lot easier than trying to find something (other than oem ecu) to run the throttle by wire and the avcs.

Either way good luck. I was originally gonna go with the XT engine then saw the difficulties of TBW and AVCS with any ecu other than the xt's. But if you feel like wiring in the XT ecu more power to ya.

Robert

I also second the thought that you should get a whole car to transplant from cuz odd little do-dads..

Also would you need a new front crossmember? I've been rattling my brain on that one for days.. HELP

Last edited by rbehny; 08-29-2003 at 11:02 PM.
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Old 09-02-2003, 10:00 AM   #7
gvmelbrty
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Quote:
Originally posted by rbehny
the cams aren't the only difference... remember the sodium filled valves aren't part of the XT package. So the short block is identical and the heads have a few differences. That sums it up.
According to this "Forester XT technical description supplement" PDF posted on the Subaru Australia web site, the XT heads do have the sodium exhaust valves:

XT Cylinder Head Features
  • Four valves per cylinder in cross flow format with straight tumble airflow being achieved by manifold and intake port design.
  • Tumble Generator Valves (TGV) for good combustion efficiency and low emissions during cold start. After starting, the TGV immediately opens to maintain good airflow and performance.
  • Twin camshaft per cylinder head, with direct valve actuation and Active Valve Control System (AVCS) variable valve timing.
  • Camshaft weight has been reduced 1700g by using a hollow shaft and an assembly of sintered cam lobes.
  • Sodium filled exhaust valve stems for low inertia and improved heat dissipation.
  • Single timing belt with self-adjusting tensioner. (100,000 km replacement interval)
Lots of other interesting XT info in that doc as well.

-tom
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Old 09-02-2003, 01:29 PM   #8
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The Forester XT block is said to be open-deck whereas the STi block is semi-closed. If that is the case, then the blocks aren't the same. I've just been too lazy to have my buddy at Subaru look up the part numbers.

-Jon
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Old 09-02-2003, 04:21 PM   #9
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Quote:
Originally posted by stimpy
The Forester XT block is said to be open-deck whereas the STi block is semi-closed. If that is the case, then the blocks aren't the same. I've just been too lazy to have my buddy at Subaru look up the part numbers.

-Jon
if you look at the pdf posted by gvmelbrty


it says...on page 8

Quote:
The Cylinder Block on the Forrester XT turbo engine features a semi closed deck design due to the higher thermal loads and pressures associated w/ a turbo engine.
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Old 09-02-2003, 11:40 PM   #10
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Huh. Guess I need to find the part numbers.

-Jon
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Old 09-03-2003, 11:36 AM   #11
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As I talked with a salesman (who had built up his own RST) he noted differences such as cast vs forged pistons along with a different turbo and intercooler. I can't remember if the rods were the same or different as well. The actual block&crank is supposed to be the same though....

I don't think the manifold can be retrofitted with a regular TB, but I haven't tried.....

Jay Storm
www.sourcemotorsports.com
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Old 09-03-2003, 12:08 PM   #12
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As far as I'm aware, the shortblocks are the same exact part number between XT and STi. I'm thinking about modding my WRX with the shortblock.

Scoob.
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Old 09-06-2003, 01:42 AM   #13
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I've thought about this swap as well. It would be a lot easier on the transmission than the EJ257, and it would still keep the torque of the RS unlike the EJ20.


I think it'll be more common once the XT has been in production a bit longer.

-Matt
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Old 09-06-2003, 03:04 PM   #14
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I think guys will be using the shortblock, I don't know about the whole motor though. There are alot of WRX guys (myself included) who are going to be using the STi block since it's relatively cheap ($1200) compared to alternatives.

You could just bolt an old intake manifold with a wired throttle to the heads. If you wanted to use the AVCS you could use an ECU/engine harness from a STI/WRX with AVCS heads and do a little splicing.
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Old 09-10-2003, 12:36 AM   #15
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Quote:
Originally posted by dwx
I think guys will be using the shortblock, I don't know about the whole motor though. There are alot of WRX guys (myself included) who are going to be using the STi block since it's relatively cheap ($1200) compared to alternatives.
$1200!!!
Is that a complete short block!?
Do either of the EJ255, or EJ257 have oil squirters for the pistions?
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Old 09-10-2003, 12:42 AM   #16
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To get the AVCS to work you could probally just use a RPM activated switch like the Honda guys do for VTECH swaps!
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Old 09-10-2003, 12:55 AM   #17
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No oil squirters, And getting the avcs to work is a lot harder then slaping on a vtec controler. It operates differently then vtec, and has been coverd many times.


I dont know about useing a sti block in my wrx. It has been said to have "high CR" and for the same price I could have an ej22 wich is a stronger block. But time will tell, Its been said that the ej257 isnt as strong as its jdm ej207 brother.
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Old 09-10-2003, 01:44 AM   #18
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I've seen the EJ257 and the EJ207 blocks together and there isn't much difference. The nature of the 2.5 motor isn't real good for running high RPM or real high boost applications. It has an enormous amount of low end and mid range power though, as we've already seen from some tuners doing minimal tuning. All depends on what you are after.

Yes it's $1200-1400 for a complete short block. Good luck finding an EJ207 block for that price. It's generally almost twice as much. As for the EJ22T you can get the block for about the same price but most people I know who have them replace the pistons and rods and increase the CR anyways.
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Old 09-10-2003, 12:45 PM   #19
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If you retain your heads from your EJ251 and use the EJ22T shortblock, you get a really low CR (7.7:1 with SOHC heads) but with the EJ255/EJ257 you get a more favourable CR of around 8.48:1
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Old 09-10-2003, 09:32 PM   #20
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So a EJ255/EJ257 block and EJ25 heads will give you a CR about:8.5?! That would be perfect for a very steertable very fast turboed motor!!!
I want one!!!
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Old 09-11-2003, 01:28 PM   #21
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Would a Forester XT ECU be simpler to set up in a WRX wagon than a WRX sedan? It seems like the layout (4dr + hatch w. wiper) would mean the controls would be nearly identical.

An XT longblock + shorter ratio XT tranny could be fun in a wagon body...
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Old 09-11-2003, 01:31 PM   #22
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The ECU doesn't handle anything like the wiper or what not. It would be the same.
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Old 09-11-2003, 02:13 PM   #23
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[Here are two dyno plots/comparison people have been waiting for:

RED Graph is with a 2.0 WRX with these mods:
Stock IC
Stock Injectors
Helix up pipe
Samco IC hoses
NGK Platinum 7s
I-Speed USA tuned ECUtek
Running 16psi

Blue Graph is a 2002 WRX with a 2004 STi 2.5 short block
Stock IC
Stock Injectors
Helix up pipe
Samco IC hoses
NGK Platinum 7s
I-Speed USA tuned ECUtek (which was the same map for the RED graph, plus a tad more fuel)
3 turbo back exhaust
VF30
Running 16psi



Next we will be Dynoing Crawford Performance wrx rebuilt heads. These will mate perfectly with our STi setup.

Let the mods begin

Chris
I-Speed USA
cescamilla@i-speedusa.com
[/quote]QUOTE]Originally posted by I-Speed USA

http://forums.nasioc.com/forums/show...&pagenumber=10

After seeing this it may just be worth it to get the short block and an ecutek reflash..... and a lot cheeper then a full swap with the new fly by wire system. And apparatly the US sti has the same deration cams as the us wrx just higher lift and avcs on the intake cam.
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Old 09-11-2003, 02:18 PM   #24
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Nice. What kind of exhaust did the 2.0L have?
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Old 09-11-2003, 09:04 PM   #25
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The 2.0 had the stock WRX exhaust. Knowing that the tdo4 would be too tiny and that the stock exhaust would hamper the 2.5 STI block , we changed them out for the dyno run.

Also, we felt that the mods we dynoed ,with the STi block, were common wrx mods that most people would already have.

Chris
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