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Old 02-11-2003, 07:00 PM   #1
Scooby Newbie
Member#: 26900
Join Date: Oct 2002
Chapter/Region: NESIC
1988 Fiero Countach
G5 Rally Car

Question What's the deal with the 2.5?

Just looked at the brochure a few days ago.

What do you think of it.

Has subaru released anymore information on the design of the 2.5 turbo motor and how it achieves 300/300 production, e.g. compression ratio, boost pressure etc? Does it use a semi-new strengthened semi-closed or closed deck block design or RS style EJ25 with different head stronger tougher internals etc. Is it designed with potential for even more output?

What's Subaru's logic behind it? U.S. lack of attacment (for now) to rally and thus the 2.0 spec? Production costs; common parts with other subarus, displacement allows JDM Sti power without requiring the JDM Sti materials for internals, valves etc.

If its as good as it sounds so far, subaru will have made their US spec cars the envy of Japanese and European enthusiasts from the exact converse in just two years!
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Old 02-11-2003, 07:20 PM   #2
Scooby Newbie
Member#: 25101
Join Date: Sep 2002
Chapter/Region: HIIC
Location: www.luanainn.com
2002 PSM WRX Wagon
1999 Twilight Blue Miata


The 2.5t uses a new engine design with a semi-closed deck. It definitely has stronger internals than a NA EJ25, but probably not as strong as the EJ207.

Top 5 reasons to develop 2.5 turbo motor:
1. Americans love torque and hate turbo lag
2. US emissions laws make a high boost turbo a booger to pass.
3. Lower stressed engine equals longer life
4. 2.5t can become the new performance engine across the Subaru lineup
5. Evo-stomping
kage is offline  
Old 02-11-2003, 09:13 PM   #3
Scooby Specialist
Member#: 18960
Join Date: May 2002
Chapter/Region: South East
Location: Bama
It lives! ; )


Just curious:

Can you say with 100% certainty that the STi EJ25 is a semi-closed design?

Why do you think the STi EJ25 wouldn't be as strong as the EJ207? Not as good of a rod-stroke ratio?

I would probably buy an STi if I knew for certain that the internals are all forged, and the block is closed / semi-closed.
n2xlr8n is offline  
Old 02-11-2003, 11:18 PM   #4
Scooby Specialist
Member#: 8351
Join Date: Jul 2001
Location: Alabama
2002 WRX Wagon


This has all been covered many times in this forum. Here is a link to the spec sheet:

Yes, the 2.5L turbo is semi-closed deck and between the press release at the Detroit Show and the spec sheet linked above, the internals are all forged (the one unknown is the crank, but according to Trey Cobb in another thread, the NA EJ25 has a forged crank, so the turbo is probably as well).

Further speculation on the strength of the motor is without basis. Once they show up and people start playing, then we'll know.

ToddStratton is offline  
Old 02-12-2003, 01:15 AM   #5
Scooby Newbie
Member#: 3541
Join Date: Jan 2001
Location: St. Charles, Mo

Originally posted by n2xlr8n
Just curious:

Can you say with 100% certainty that the STi EJ25 is a semi-closed design?

This info has been on Subaru's official STi release site since day one of Detroit. You must have been under a rock for the last month!!

GaryS is offline  

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