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Old 06-26-2003, 12:28 AM   #1
obyone
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Default STI and Forester XT engine differences

So I was at the dealer yesterday and they had a Forester XT sitting in the showroom. Now normally I wouldn't look twice at the Forester but it just beckened me with it's totally gorgeous Java Black paint job. If you haven't seen the Java Black color, you are defiantly missing out on one sweet black.

So, I start re-evaluating my need....well, ok.....my want for an STI. I was thinking, the WRX is starting to get a little played out with all these kids that are getting one for their 16th B-day (no offense to those who are truely mature about their new rides) and the STI is no where in sight for anything resembling a decent price. The Java black sure gave the XT some points. But I'm getting off the subject.

Seeing as how the STI and the XT run 2.5T engines, what are the differences between them? I'm not assuming that this is akin to the EJ25 with just a turbo on it...no no. I'm assuming these two powerplants differ in many ways, I'm just curious in which ways they differ.
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Old 06-26-2003, 05:18 PM   #2
obyone
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Sooo...umm....does anyone know?
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Old 06-26-2003, 06:22 PM   #3
Rummy
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forrester is missing about 90 hp... for starters
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Old 06-26-2003, 06:25 PM   #4
Subie2
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I know the XT has a much smaller IC up top.

Chris
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Old 06-26-2003, 06:43 PM   #5
well_armed
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Active Valve Control System (AVCS), Better/Stronger Engine internals (cams, pistons, etc...), larger turbo/intercooler setup; all which generate a much larger increase in horsepower....and let me tell you, the STi isnt your father's WRX
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Old 06-26-2003, 07:38 PM   #6
jimqpublic
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Default Somebody with the parts CD will know

But for starters:

STI is EJ257
XT is EJ255
(as posted elswhere on this site.)

Both appear to have the same short block
Both have AVCS
Both have sodium filled exhaust valves

EJ255 probably has way more torque from idle to about 3600 rpm's. Advertised torque is 235@3600, 197@5600 (based on 210 HP@5600)

EJ257 definitely has way more torque from about 3600 rpm to redline. See http://www.vishnutuning.com web site for a graph with a very steep wheel torque curve from 115 lb*ft at 2400 rpm to 215 lb*ft at 4100 rpm. Advertised torque is 300@4000, 263@6000 (based on 300 HP@6000).

Somebody please buy one of each and see which parts are the same. Also there have been comments that the XT has the same or possibly a smaller turbo than the WRX. Intercooler is definitely smaller than the WRX and waay smaller than the STI.

Jim
Waiting for the Baja Turbo
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Old 06-27-2003, 03:08 PM   #7
T-WRX
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On a related note . . . C&D just published a 5.3 second 0-60 time for the Forester XT, and their review stated that the engine was much more powerful at low rpm than the 2.0T or the 2.5NA.
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Old 06-27-2003, 03:31 PM   #8
lstepnio
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I've been watching for details on the XT EJ255 really closely. I'm playing with the idea of swapping the XT EJ255 motor into the New Age Impreza WRX 5MT. It should much cheaper than any of the stroked 2.2-2.5 built motors.

It seems that one would need to address a few issues to get EJ257 STi power levels out of the XT EJ255 motor:

1. ECU
2. Turbo
3. Intercooler
4. Injectors
5. Fuel Pump

I know that CobbTuning(I'm sure other tuners as well) is currently working the XT ECU reflashes. The bolt on stuff should be easy and just a matter of tuning the ECU once the XT reflashes are available.

Has anyone verified that the EJ255 motor will just simply drop into the New Age Impreza 5MT?
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Old 06-27-2003, 06:28 PM   #9
jimqpublic
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These spec's are from the STI specs and Baja Turbo specs .pdf files found at:
http://www.media.subaru.com

Description XT/Baja EJ255 STI EJ257

Block: Same description- Specially reinforced die-cast aluminum with integral cast iron cylinder liners, five main bearings, semi-closed deck cylinder design

Displacement: 2,457 cc (150 cu. in.)

Bore x Stroke: Same 99.5 x 79 mm (3.92 x 3.11 in.)
Heads/Valvetrain: Aluminum alloy cylinder heads with double overhead belt-driven camshafts (DOHC), four valves per cylinder, Subaru AVCS (Active Valve Control System) variable valve timing and
sodium-filled exhaust valves.

Compression ratio: 8.2:1 (Note: I have read elsewhere that the EJ 255 has an 8.5:1 ratio due to its lower boost level.)

Max. boost pressure: 11.6 PSI 14.5 PSI

Horsepower: 210 @ 5,600 rpm 300 @ 6,000 rpm

Torque: 235 @ 3,600 rpm 300 @ 4,000 rpm

Fuel/Induction: Sequential multi-port fuel injection (MFI) with multi-spray injectors and Tumble Generator Engine management Valves, electronic drive by wire throttle, turbocharger, intercooler (Note: STI mentions high pressure turbocharger and intercooler water spray)

Ignition: Direct
Firing order: 1-3-2-4

Also mentioned on the media web site "at a glance" sheets are that both engines use sodium filled exhaust valves.
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