96 DOHC EJ25 and new DOHC ej25 differences

biggreen96 · 07-06-2003, 08:04 PM

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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rhdude · 07-09-2003, 10:14 AM

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...

Albert · 07-09-2003, 04:16 PM

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.

SUBE555 · 07-09-2003, 06:47 PM

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.

biggreen96 · 07-09-2003, 08:38 PM

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?

Albert · 07-09-2003, 09:10 PM

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

biggreen96 · 07-16-2003, 03:59 AM

any body have ecu pin outs for 96 and 97 legacys?

SubyTechMaster · 07-17-2003, 12:48 AM

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

Jaxx · 07-17-2003, 12:58 PM

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?

biggreen96 · 11-13-2003, 09:04 AM

bump

subysouth · 11-13-2003, 12:46 PM

97 2.5L motor

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

From my owners manual

ss

07-06-2003, 08:04 PM	#1
biggreen96 Scooby Specialist Member#: 12535 Join Date: Nov 2001 Chapter/Region: NWIC Location: Idaho slash Washington Vehicle: vf39 93 Legacy Wagon 92 Legacy Rally EG33'd	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? * Registered users of the site do not see these ads. Last edited by biggreen96; 07-09-2003 at 08:40 PM.

07-09-2003, 04:16 PM	#3
Albert Scooby Specialist Member#: 3288 Join Date: Dec 2000 Location: San Diego, CA. USA Vehicle: 1998 Impreza 2.5RS Rally Blue Pearl	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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07-09-2003, 10:14 AM	#2
rhdude Scooby Guru Member#: 6637 Join Date: May 2001 Chapter/Region: MAIC Location: Manassas Vehicle: 2009 Acura MDX Sport	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...

07-09-2003, 06:47 PM	#4
SUBE555 Scooby Specialist Member#: 24043 Join Date: Sep 2002 Chapter/Region: MWSOC Location: Neenah, WI Vehicle: 2005 Legacy GT Sedan Silver	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.

07-09-2003, 08:38 PM	#5
biggreen96 Scooby Specialist Member#: 12535 Join Date: Nov 2001 Chapter/Region: NWIC Location: Idaho slash Washington Vehicle: vf39 93 Legacy Wagon 92 Legacy Rally EG33'd	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?

07-16-2003, 03:59 AM	#7
biggreen96 Scooby Specialist Member#: 12535 Join Date: Nov 2001 Chapter/Region: NWIC Location: Idaho slash Washington Vehicle: vf39 93 Legacy Wagon 92 Legacy Rally EG33'd	any body have ecu pin outs for 96 and 97 legacys?

07-17-2003, 12:48 AM	#8
SubyTechMaster Scooby Specialist Member#: 4423 Join Date: Feb 2001 Location: Placerville, CA USA Vehicle: '04 08 Tribeca, SVX Gold, Maroon	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

07-17-2003, 12:58 PM	#9
Jaxx NASIOC Supporter Member#: 177 Join Date: Aug 1999 Chapter/Region: NWIC Location: Boise,Idaho,USA Vehicle: The 93 Imp W/EJ20K flat black	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?

11-13-2003, 09:04 AM	#10
biggreen96 Scooby Specialist Member#: 12535 Join Date: Nov 2001 Chapter/Region: NWIC Location: Idaho slash Washington Vehicle: vf39 93 Legacy Wagon 92 Legacy Rally EG33'd	bump

11-13-2003, 12:46 PM	#11
subysouth Scooby Guru Member#: 5039 Join Date: Mar 2001 Chapter/Region: South East Location: Ocean Springs, MS Vehicle: 2007 Outback XT Grey 5-speed	97 2.5L motor engine model EJ25D timing ????? Bore 3.92" Stroke 3.11" CR 9.7 to 1 From my owners manual ss