Swapping a 2.5l dohc out for a 2.2l sohc

Heads, valves, pistons, rods, crankshaft, etc...

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thatsme87
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Swapping a 2.5l dohc out for a 2.2l sohc

Post by thatsme87 »

I am trying to swapp a 2.5l dohoc phase 2 1999 Subaru outback to a 2.2l sohc engine phase 2 block and heads with a phase 1 non emission s intake on it out of a 1998 Subaru legacy sedan and i am wondering what i need to do to make this work because currently the intake plugs are different. i am wondering if i could take the intake for the 2.5l engine and run it on the 2.2l engine? Or if i could get a phase 2 2.2l intake and run it on the 2.2l engine and have it match the wiring harness i have in the 2.5l dohoc phase 2 out back currently with very little changing out of the harness or computer kinda at a loss with what to do.
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by Legacy777 »

You need to match the intake manifold to the heads. I do not know whether the 2.5 intake manifold will match up to the 2.2 heads. Hopefully others will chime in.

The other thing you need to keep in mind is the ECU. I would suspect there will be some differences in the ECU between the 2.2 & 2.5 motors...not to mention the ECU connectors and other various electronics.
Josh

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thatsme87
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by thatsme87 »

Okay cool i am still looking trying to figure out how that all works. Yet
mike-tracy
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by mike-tracy »

The 1999 is a "special" car with a mix of phase 2 and 1 electronics.

Do you want to do the minimum of work and have a reliable running car with virtually no incompatibilities?

Your best bet is to throw those ej25d heads on a different block (whether that is an ej251, ej25d, ej22e, etc).

If your car is auto, then the only ecu's that will work are going to be from an ej25d 1999 legacy. Putting a different ecu in there will cause a permanent check engine light.

To answer your question about the intake directly, the phase 1 and 2 SOHC intakes don't interchange due to different bolt pattern and port spacing. Same thing with phase 1 ej25 (dohc) and phase 2 ej25 (sohc and JDM DOHC).

In theory you could put the phase 2 wiring harness on a phase 1 intake and solder in the old style plugs as needed. And vice versa.

But as I said, unique car with unique mixed generational electronics. Best to keep it as close to what it came with from the factory.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
thatsme87
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by thatsme87 »

I am looking at the 2.2l engine and it appears to have the newer style heads on it, making me think this is a Phase 2 cylinder head. however it is a none emissions engine and has one less electrical plug on its intake, then the intake does on the 2.5l; also it has a different style of electrical plugs, one is gray and one is brown, and they defiantly don not match up to the 99's plugs, not sure if the color tells anything. this is all on the old intake. On the intake off the 2.5l engine are 2 light gray electrical plugs that are different shape, then there is a third plug that is off white and smaller than the others that I would guess must be for the emissions side, also this intake has a large idle air control valve on the side of it. Now if the block and heads were a phase 2 could I bolt up a 2.2l phase 2 intake and what are the chances of the plugs and ECU working with the first go. I totally get the keeping it as close to factory as possible. the original engine is pretty much toast do to the left side dohoc cam pulley breaking apart well on the freeway so the left head is pretty well shot. I am not sure how the pistons faired. I had a 2.2l engine already and was hoping to be able to trade it in and have a decent running car with a little power loss.
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by mike-tracy »

The ej25d-engined 1999 legacys all had phase 1 engine wiring, mixed with phase 2 transmission electronics.

The ej22-engined 1999 legacys had phase 2 engine and transmission wiring.

That makes the ecu the problem main. There's no ej22 ecu that supported phase 1 engine and phase 2 transmission.

In older 2nd gen legacys (95-98) the wiring was 100% phase 1, so you could plug in an ej25d or ej22e and simply plug the ecu to match. No wiring changes or incompatibilities with plugs or etc.

But due to the 1 year only mismash of the elextronics, and ecu incompatibilities (I dealt with those with my 1999 Legacy SUS, literally only the 1999 Ej25d ecu would work property), you are stuck running an ej25d or making a hybrid engine that reuses the electronics AND wiring harness from that ej25d engine.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by mike-tracy »

If all you're trying to do is trade the car in, I'd look around for 1 or both ej25d heads and put those on. The ej25d heads don't have to be from a 1999.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
thatsme87
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Re: Swapping a 2.5l dohc out for a 2.2l sohc

Post by thatsme87 »

Thank you its great info, I was hoping it was a little easier than that for the 99's but I guess I'll have to go back and decide what to do now with that.
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