2.5 Info needed

[suba]

My engine is getting a bit tired so I've been looking at engine options. I'm aiming for a bit more power if I decided to invest the time and money in this car (90 N/A) so I figure I can either do a ej22t swap or the 2.5 swap. I have a potential line on a low mileage (<75k) 2.5 so I'm leaning that direction at the moment. The engine is from a 2001 outback so I have a few questions about the 2.5 engines:

1) All the 2.5's are SOHC after 98 correct?

2) Are all the 2.5's from 98 to 2003 identical, mechanically and electrically?

I know that the 2.2 ECU can run a 98/99 2.5 without major changes (albeit with rather aggressive timing) so I want to make sure this is an option with later engines as well before I look further in to this.

[wtdash]

My engine is getting a bit tired so I've been looking at engine options. I'm aiming for a bit more power if I decided to invest the time and money in this car (90 N/A) so I figure I can either do a ej22t swap or the 2.5 swap. I have a potential line on a low mileage (<75k) 2.5 so I'm leaning that direction at the moment. The engine is from a 2001 outback so I have a few questions about the 2.5 engines:

1) All the 2.5's are SOHC after 98 correct?

2) Are all the 2.5's from 98 to 2003 identical, mechanically and electrically?

I know that the 2.2 ECU can run a 98/99 2.5 without major changes (albeit with rather aggressive timing) so I want to make sure this is an option with later engines as well before I look further in to this.

Hi,
I'd look over @ Ultimatesubaru.org/forum and RS25.com too. There's also a write-up, or 2, on here and/or USMB about putting a EJ25D into the '90-94 Legacy......not sure about the '01 OB's 2.5.

Here's what I know:
1. No, the 2.5 stayed DOHC on the Legacy model line - GT/Outback - thru '99. But they did all ago to the Phase 2 block. So it's: Phase 1 EJ25D w/DOHC = '96-'99 Legacy (GT/LSi/OB) and '98 Impreza RS/Forester. Phase 2 EJ25 SOHC = '99+ Impreza/Forester. Phase 2 EJ25 DOHC = '99 Legacy (GT/OB).

2. All 2.5s from '00-03 should be the same, but I think there was some MAF vs. MAP based differences. Check out the EJ Wikipedia site.

I usually think the ECU compatibility depends on SOHC vs. DOHC, since the SOHC went to MAP-based in '99. I know from experience that a '99 EJ25 Outback ECU will run a '95 EJ22e...I did the swap.

Also, remember the '99 Phase 2 block and transmission went to 8 engine/trans mounting bolts vs. the earlier 4. YOU CAN still put the Phase 1 4-bolt EJ22/EJ25 in front of the Phase 2 8-bolt trans, as I did on my '99 swap. There'll just be unused bolt holes, which is OK. If you go the reverse direction - Phase 1 block w/Phase 2 trans, you'll only have 1 mounting bolt for the starter. It works, but some like to drill/tap another one.

The intake manifolds are not interchangeable between Phases. Your '90 SOHC IM won't fit the '01 OB, and the cam/crank signals are different on the '01 vs. the '90. Do some research on that, too.

GL, Td

[suba]

Okay, I think I understand.....man they did some confusing mixing of parts.

I'm not too concerned about MAP/MAF based as with a swap I would probably use the 2.2 TB and figure out a way to put the 2.2 IAC on the 2.5 intake. If I can i'm going to try and used the 2.2 ecu and initially run high octane (91) fuel until I can potentially remap the ignition curve in the ecu (there is a thread on here about a tuning tool int the works for N/A first gens). I know I would have to repin the igniter plug, though depending on what else can be switched much of it should stay the same.