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Old 07-06-2003, 08:04 PM   #1
biggreen96
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Default 96 DOHC EJ25 and new DOHC ej25 differences

Does anybody know the differences between the 96 EJ25 DOHC and 97 EJ25 DOHC?

My 96 makes 155 TQ @2800 and 155 HP @5600. It also requires premium fuel.

The 97+ EJ25's make 11 and 10 more respectivly.

96 EJ25 -
timing 15B
bore 3.92
stroke 3.11
CR 9.7 to 1

97 DOHC
timing ?
bore ?
stroke?
CR ?

What vital systems are different? Any added sensors?

I want to know how to get the extra power into my 96. Could it be as easy as an ecu swap?
I just dont understand how the newer EJ25 makes more power and requires less octane than the 96 even with the higher CR. Tuning obviously but how do I benefit?
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Last edited by biggreen96; 07-09-2003 at 08:40 PM.
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Old 07-09-2003, 10:14 AM   #2
rhdude
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the '98 RS has a lower compression than 10:1... I think its like 9.5:1...


but, in general, on N/A cars, higher compression means more HP...
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Old 07-09-2003, 04:16 PM   #3
Albert
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My understanding is the 98 RS and 98-99 Legacy share identical engines. The 96-97 were also the same except they required premium fuel due to a different ecu.



That said ALL engine specs on my 98RS EJ25D are identical to what you list for your '96, compression, and timing are also identical.

The only external differences I recall seeing on some 96-97's are the coilpack connectors and the intake tube. I suspect the difference is infact the ecu.



edit:
I'm no tec-geek, so I did consult my glovebox manual first to confirm... and it's the same.

Last edited by Albert; 07-09-2003 at 04:24 PM.
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Old 07-09-2003, 06:47 PM   #4
SUBE555
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My '97 Legacy GT doesn't require premium fuel, never has. I think the CR is something like 9.7:1-10.0:1.

I always wondered what the differences were. The reason for the power difference is probably using a less combustable fuel with slightly lower compression. Aside from that I am not sure what makes the necessity for the premium fuel.
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Old 07-09-2003, 08:38 PM   #5
biggreen96
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can you check in your owners manual to see the exact CR number? your 97 is DOHC right?
And if nothing mechanicaly changed it seems an ecu swap will give me more power and let me use lower octane fuel. Something else had to have changed.
Maybe cams are different?
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Old 07-09-2003, 09:10 PM   #6
Albert
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Quote:
Originally posted by SUBE555
My '97 Legacy GT doesn't require premium fuel, never has. I think the CR is something like 9.7:1-10.0:1.
Hey SUBE555, What's the production date on your GT? Is it also a EJ25D series? Do you have a straight intake tube or is it one with the black air box immediately before the throttle body?
Go fiigure...the '97 GT I tested during the Christmas break of '96 was one that required premium fuel
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Old 07-16-2003, 03:59 AM   #7
biggreen96
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any body have ecu pin outs for 96 and 97 legacys?
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Old 07-17-2003, 12:48 AM   #8
SubyTechMaster
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In '97 Subaru reduced engine friction in many ways and also changed the FI map.
Changes:
'96 Hydraulic valves, '97 adjustable valves
'96 2mm offset wristpin, '97 .5mm offset
'96 skirted pistons, '97 skirtless pistons
(The combination of wristpin offset and skirtless piston produced the notorius "piston slap" noise)
'97 increased compression and also became an interferance motor (9.7/1 iirc)
Only '96 requires premium fuel
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Old 07-17-2003, 12:58 PM   #9
Jaxx
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intersting .. that might very well make the 96 the best 2.5 for an aftermarket turbo setup . maf/ lower compression/ noninterfearance

ed do you think that you woudl be able to run a 96 with a 97 ecu and gain performance/ability to run less than preimum fuel?
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Old 11-13-2003, 09:04 AM   #10
biggreen96
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bump
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Old 11-13-2003, 12:46 PM   #11
subysouth
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97 2.5L motor

engine model EJ25D
timing ?????
Bore 3.92"
Stroke 3.11"
CR 9.7 to 1

From my owners manual

ss
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