EJ25E management run EJ25D or EJ251?

[el_freddo]

As title suggests - can the EJ22E engine management run the EJ25D (with original heads)? 

The EJ251 with EJ22E combo becomes a frankenmotor if I’m not mistaken - works well? 

Asking as my L series is EJ22E converted. I reckon the extra torque of the 25 is desirable but to get the 251 in I don’t want a rewire job as that’s basically another whole conversion I can be bothered with. 

I haven’t done much research on this recently as it’s a bit of a spur of the moment idea before a mate heads over from the west to do an epic two week trip over my way... though an engine swap might perk Ruby Scoo up a bit more again. 

I have a complete EJ25D at my disposal. The EJ251 would need a parts yard run and I wouldn’t be particularly confident in one of those unknown engines. And I can’t see my sister killing her Gen3 RX Liberty anytime soon for me to nab the engine from it. 

Cheers 

Bennie

[heartless]

offhand, i am going to say no...

the frankenmotor uses the 25 block, with the 22 heads & intake... ECU i believe needs to match the upper portion, ie all the sensors and such

[idosubaru]

14 hours ago, el_freddo said:

As title suggests - can the EJ22E engine management run the EJ25D (with original heads)? 

Yes. All day long.  I’ve swapped a bunch of Phase I EJ22 and EJ25 ECUs and  they all perform identically with exactly the same long term gas mileage. 

Edited February 9, 2021 by idosubaru

[el_freddo]

Thanks @idosubaru and @heartless

I’ll have to swap the HGs before it goes in. That will be the decider I reckon. 

Cheers 

Bennie

[idosubaru]

6 hours ago, el_freddo said:

Thanks @idosubaru and @heartless

I’ll have to swap the HGs before it goes in. That will be the decider I reckon. 

Cheers 

Bennie 

 

Are you wanting to just swap in an EJ25 block in place for an EJ22 and retain the EJ22 heads intake and ECU?

If so - yes you’re good.

If you’re wanting to use the EJ25D manifold then this is more nuanced.

In the US the EJ25D manifold is plug and play into 1995-1998 EJ22s but not 1990-1994 just because the connectors are different.  

you might want to be a little more clear what you’re doing before I lead you astray!!

[GeneralDisorder]

Need to watch your compression ratio. A 251 with 22E heads is well above 12:1 and is much too high even for premium fuel. EJ25D is between 9.5 and 10.5 depending on 96 or 97-99 pistons. You can use the 25D pistons in the 251 block but you still must use the thick 25D HG's.

As for the 22E management running the 2.5. Yes it will run. No it will not be optimal. Closed loop will correct idle and cruise fueling. Timing will not be correct or optimal, neither will power enrichment or knock control (different bore size and sensor frequency). 

GD

Edited February 9, 2021 by GeneralDisorder

[el_freddo]

Thanks gents! 

Looks like it’s a bit more involved than I first thought. 

On 2/9/2021 at 1:19 PM, idosubaru said:

Yes. All day long.  I’ve swapped a bunch of Phase I EJ22 and EJ25 ECUs and  they all perform identically with exactly the same long term gas mileage. 

 

10 hours ago, GeneralDisorder said:

As for the 22E management running the 2.5. Yes it will run. No it will not be optimal. Closed loop will correct idle and cruise fueling. Timing will not be correct or optimal, neither will power enrichment or knock control (different bore size and sensor frequency)

So EJ22E ECU will run the EJ25D with its factory DOHC heads, but not at the best it could if I was running EJ25D management, correct? 

If that’s the case it would probably more beneficial for a complete EJ251 swap with matching management. 

Thinking I’ll just be happy with the EJ22 ;)

Cheers 

Bennie

[idosubaru]

4 hours ago, el_freddo said:

Thanks gents! 

Looks like it’s a bit more involved than I first thought. 

 

So EJ22E ECU will run the EJ25D with its factory DOHC heads, but not at the best it could if I was running EJ25D management, correct? 

If that’s the case it would probably more beneficial for a complete EJ251 swap with matching management. 

 

 

No - you're conflating a lot of different variables and ideas that don't mix.  No one knows what you're trying to do and you're mixing up frankenmotor verses engine swap verses piston swap information.

Let us ASSUME you have the US 95-98 style EJ22:

Remove it and install the EJ25D. Done - it'll run perfectly fine. People do it all the time. 
You may or may not need a different manifold and minor EGR tweak but we can't answer that until we know what motor you have..."EJ22E" isn't enough.  Which one? 

If you wanted the EJ25D ECU - remove the EJ22 ECU and plug in an EJ25D ECU.  The wiring is the same and they're plug and play compatible.  No big deal.  But I've done it and noticed zero difference in 160,000+ kilometers of using various ones.  It's a complete waste of time for me. 

If you're doing a frakenmotor then maybe the compression changes things (depending what you do), but people install frankenmotors all the time without issues and without messing with engine management or wiring - it's commonplace.  And they run fine and they aren't installing standalones.  GD is also installing stand alone power management and doing huge engine builds.

So sure, compared to NASA the stock ECU is lower grade.  For your purposes - it's probably worth looking into what other DIY folks are doing verses 5 digit budgets.

 

 

[idosubaru]

5 hours ago, el_freddo said:

So EJ22E ECU will run the EJ25D with its factory DOHC heads, but not at the best it could if I was running EJ25D management, correct? 

If that’s the case it would probably more beneficial for a complete EJ251 swap with matching management. 

 

No - that's a terrible way to look at it if you're just asking which engine swap to do - EJ25D or EJ251. 

For an EJ25D you simply install the EJ25D and EJ25 ECU - they're plug and play compatible (caveats in last reply because you haven't given us enough info)

For an EJ251 you'd need hours of wiring work and splicing. 

So the EJ25D "wiring" and "ECU" work would take 15 minutes....the EJ251 would take 15 hours.  Completely different orders of magnitude. 

[el_freddo]

Thanks Idosubaru. 

I have an Gen1 series 2 EJ22E, from about 1991-1994 Australian Domestic Market model. 

Injectors are red units, not the earlier grey ones. 

If it’s as simple as sliding the EJ25D under the EJ22E manifold, or just plugging in the engine harness from the EJ25D to that of the EJ22E management, this would be the easiest way to go. One of the reasons for this is because I have an immobiliser imbedded in my cutdown loom that I really don’t want to try pulling out (over here an approved immobiliser must have wiring all the same colour - black). 

If I need to swap pistons IF doing the frankenmotor, I would rather be doing the full EJ251 engine and management conversion instead - is what I meant to convey in my previous post. This may see a new immobiliser, or at least a kill switch

The ultimate plan is to finally get my L series engineered - and if I’m going to do that I might as well engineer it with the EJ25 conversion of some sort rather than the EJ22 (which is still a great engine). I need the vehicle to be engineered to be eligible for club registration (costs about 10% of full registration). And over here, it should be anyway...

All of this work comes down to time and a little bit of money. With a relatively young family I’m finding my shed time is smaller than ever which is frustrating. And needing the L for a big trip in September makes it tricky when I still need to be completing work on my brumby (small resto stuff), the RS turbo project (Gen1 Liberty, you guys got the SS) and the other maintenance on our daily drives. Not a great shed to work in either, but it’s better than nothing. 

The idea came about because I have an EJ25D at my disposal. It ran well when the vehicle (also an L series) was retired. Wiring is there but not in a great state, no ECU. It would be interesting to plug in an EJ22E ecu and see if I can get it going (after a bit of other work for power etc to the wiring). 

The EJ251 idea comes from experience with my sister’s RX liberty and my MIL’s SG forester.

I hope this sheds some light on where I’m at  

Cheers 

Bennie

[idosubaru]

Great - that’s perfect.  I’m going to assume your 90-94 engine is the same as our 90-94.

Here’s the easy way for you:

Bolt your EJ22 heads to the EJ25D block and then use your EJ22 intake manifold. It’ll be as if nothing changed. 
 

It’ll bolt right in, no wiring, no ECU needed and you’ll have new headgaskets (EJ25D headgaskets - match the gasket to the block).

If you wanted to run the entire EJ25D engine and not swap heads then you would look into simply installing your EJ22 wiring harness onto the EJ25 intake manifold.

You can do this with 95-98 EJ22s but I’m not sure about 90-94s.

when swapping a 95-98 EJ22 and EJ25D you swap the entire engine - plug and play compatible.  The wiring connectors are identical.   You can’t swap manifolds as the EJ22 doesn’t fit onto the EJ25D.  But there’s no need as the wiring is plug and play anyway. 

But this also means you can’t just bolt your 90-94 manifold onto the EJ25D. Hence you’d have to see if you can swap your harness onto the 25 manifold. 

the 90-94 intake manifolds are the same bolt pattern as 95-98 EJ22 so they’re interchangeable physically, But the electronics are different.  

[el_freddo]

Awesome and clear info there @idosubaru!! 

Can I use the MLS EJ25 head gaskets, end of part number being 664 and 774 (going badly by memory) on the EJ25D block with EJ22E heads? Or do I need to use the factory EJ25D head gaskets?

Cheers 

Bennie

PS: side note for those playing at home, in AUDM land, we didn’t get the single port EJ22, all of ours are dual port. Fun fact  

[el_freddo]

These Hg part numbers is what I was referring to (badly!): 

Subaru Head Gasket 11044AA642

Subaru Head Gasket 11044AA770 

Thanks to @forester2002s for sharing in another thread  

Cheers 

Bennie

[idosubaru]

7 minutes ago, el_freddo said:

Awesome and clear info there @idosubaru!! 

Can I use the MLS EJ25 head gaskets, end of part number being 664 and 774 (going badly by memory) on the EJ25D block with EJ22E heads? Or do I need to use the factory EJ25D head gaskets

PS: side note for those playing at home, in AUDM land, we didn’t get the single port EJ22, all of ours are dual port. Fun fact  

The 610 EJ25D headgasket is MLS - use that, resurface heads, clean surfaces, and clean and lube head bolts. 
Nifty on the dual port.  Ours were 90-95 only, and all EJ25's of course.

[idosubaru]

2 minutes ago, el_freddo said:

These Hg part numbers is what I was referring to (badly!): 

Subaru Head Gasket 11044AA642

Subaru Head Gasket 11044AA770 

Thanks to @forester2002s for sharing in another thread  

Cheers 

Bennie

Those are later EJ25's. 

you want the 610 gasket: 

https://parts.subaru.com/p/Subaru__/Engine-Cylinder-Head-Gasket-Top-End-Engine-Gasket/49500367/11044AA610.html

Edited February 12, 2021 by idosubaru