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overdeveloped beater
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Nope. SOHC manifold bolts are offset like this: .o' 'o.

DOHC manifold bolts are inline like this: .o. .o. (bolts are centered on ports).

Additionally, it looks like the port placement is different, as in the SOHC ports sit further from the centerline of the crank than the DOHC does. I noticed the difference when I hung both types of manifold up side by side. I posted measurements over on nasioc after someone made an adapter plate.....
 

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1998 Forester on Orange 57F
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Storm said:
Nope. SOHC manifold bolts are offset like this: .o' 'o.

DOHC manifold bolts are inline like this: .o. .o. (bolts are centered on ports).

Additionally, it looks like the port placement is different, as in the SOHC ports sit further from the centerline of the crank than the DOHC does. I noticed the difference when I hung both types of manifold up side by side. I posted measurements over on nasioc after someone made an adapter plate.....
Well this info is right for the ej25 DOHC and ej25 SOHC.. But what are these "DOHC heads". The SOHC manifold bolts right up to WRX DOHC heads. Also the ej257 heads or any of the JDM GD heads.
 

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Hmm so this would mean I could run an older 93 1.8L intake manifold on a set of DOHC heads. The 1.8's are taller than the 2.5's might be good for a few more pound of torque.
 

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EJ20 said:
as I know they will fit fine, but it has somthing to do with the wiring ( correct me if I'm wrong! ) I guess you cann't run sohc ecu with dohc manifold

If you tap the manifold for a MAP sensor and cap off the EGR valve port and work around the vacume idle control it should work fine. Why would you want to go to DOHC heads and manifold?
 

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overdeveloped beater
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If you get a SOHC EJ25 manifold to bolt to 98 or older DOHC heads (as discussed in this thread), you are some sort of magician.

The EJ18 manifold won't bolt to the DOHC heads or the new style SOHC heads.
 

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suby2.5 said:
The 97 heads should be ej22 if they are factory units.
:confused: On an Outback? Not an Outback Sport, an Outback. The '97+ Outbacks came with the same DOHC EJ25 that was in the 2.5GT, so unless someone at the factory really screwed up he's got EJ25 DOHC heads.
 

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Patrick Olsen said:
:confused: On an Outback? Not an Outback Sport, an Outback. The '97+ Outbacks came with the same DOHC EJ25 that was in the 2.5GT, so unless someone at the factory really screwed up he's got EJ25 DOHC heads.
My bad I should have read slower. So yes phase I motor.
 

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2000 RS 2.5 SRP Coupe
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Discussion Starter #13
Can anyone confirm for me that the heads on a 97 Outback 2.5L DOHC motor are the same heads as on the 98 RS DOHC motor?
 

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overdeveloped beater
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I can confirm that. The 96 Outback however, uses a different head...some say better as it is the same casting as the VIII head and uses HLA's instead of shim over bucket. The 97 EJ25D uses the same heads as the 98EJ25D for sure.
DTSJR said:
Can anyone confirm for me that the heads on a 97 Outback 2.5L DOHC motor are the same heads as on the 98 RS DOHC motor?
 
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