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Will a SOHC ej25 head mate with an SOHC ej22 block?

ej22 ej25 legacy 1999 legacy WRX frankenmotor

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12 replies to this topic

#1 Multisurface_Subaru

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Posted 17 August 2017 - 11:41 AM

I'm attempting to turbo my N/A ej22, car is a 1999 Legacy L 30th Anniversary edition. I don't see why a phase 2 ej25 head won't mate up with the phase 2 ej22 block and they are both SOHC but I know that there is greater wisdom than I posses lurking in these forums. My ej22 block has single port heads and I want to swap them our for the ej25 duel port heads in order to run boost. 

what issues do I face?

will the heads mate right up to the ej22 in a "plug and play" way?

will my stock ECU know what to do with the ej25 cam? 

Any general advice?

 

I will also be switching the full intake manifold so advice on that would be greatly appreciated.  :)

Are there different sensors I need to be aware of? 

Line placement issues?



#2 86BRATMAN

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Posted 17 August 2017 - 11:58 AM

You'll need to use your original LH cam gear, use the complete ej221/2 intake manifold and sensors, and a dual port exhaust obviously. Other than that it's straightforward.

The problem with running boost is going to be the 10:1 compression.

#3 GeneralDisorder

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Posted 17 August 2017 - 01:35 PM

"Any general advice?"

 

Don't do it unless you have alternate transportation and money to burn on this learning experience. It's not going to be *if* you blow up the engine, it's going to be how many of them you blow up before you figure out how to do it and make it somewhat reliable. I'm going to say 3 - either you figure it out by the third engine, or you give up after that many failures. 

 

GD


Edited by GeneralDisorder, 17 August 2017 - 01:39 PM.


#4 wtdash

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Posted 17 August 2017 - 02:01 PM

The problem with running boost is going to be the 10:1 compression.

 

^QFT



#5 Multisurface_Subaru

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Posted 17 August 2017 - 05:07 PM

"Any general advice?"

 

Don't do it unless you have alternate transportation and money to burn on this learning experience. It's not going to be *if* you blow up the engine, it's going to be how many of them you blow up before you figure out how to do it and make it somewhat reliable. I'm going to say 3 - either you figure it out by the third engine, or you give up after that many failures. 

 

GD

The car in question is one out of four cars I own, the other three run reliably. It's a project car, I bought it to tear it apart and mess with. Funding is not an issue either, right now I'm feeling out directions to take with it wether it be swapping the heads, turboing the existing motor or buying another motor to swap in. 



#6 matt167

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Posted 17 August 2017 - 08:07 PM

You can do anything you want with that. Sky is the limit with that chassis/ ECU when you mix in some tuning and JDM parts and what you need is not expensive.

 

The 1999-2000 EJ221/222 is MAF based, meaning it can adjust for boost up to a point without any tuning at all. 5-8 PSI will run on one of them. Use a voltage clamp, and a 6:1 RRFPR for safety.. You can't crank the boost with 10:1 but that is about the safe limit. You can go to RS25 to find plenty of builds. Problem you will have is the turbo parts don't actually fit. The Up pipe will not clear SOHC heads. There used to be someone making conversion up pipes but he quit doing it. He made them both Single and Dual port though.

 

What I would do is a 1998-2001 JDM EJ205. They are the ones sold as Non AVCS and have plug wires.. They are directly swappable into the 1999-2001's that have JECS ECU's ( you would need to check ) The idle air, throttle body and ignition and cam triggers all match what the 1999-2001's do with JECS ECU's. No surprise as they ran JECS ECU's.. After that, you can get Project Lambda tuning for about $400 and you then can tune the EJ205 to run on the factory ECU without a full harness swap. All you need to do is install your engine harness on the EJ205, possibly extend a wire or 2 and swap the USDM coil on as the connector is different.



#7 86BRATMAN

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Posted 17 August 2017 - 08:58 PM

Every phase 2 ej22 I've encountered has ran the 32-1-1 trigger pattern with iacv, tps, and map setup like the usdm 02-05 ej205. The 99-04 ej25 cars (mostly) use the 6/7 triggers like the v5/v6 ej205/7.

#8 matt167

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Posted 17 August 2017 - 10:02 PM

I wasn't sure. I know the 32-1-1 trigger means it's a Denso ECU and thus work on USDM EJ205 electronics minus needing plug wires.. Getting a set of DOHC plug wires with male coil ends might be impossible though. The EJ205 wires have a short and long side since the coil is offset.

 

No tuning available for the early Denso ECU's though so it has to be ran conservative.



#9 GeneralDisorder

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Posted 18 August 2017 - 12:48 AM

Buy a wrecked USDM WRX. It will be much easier. JDM EJ205's are super cheap..... Either way though - 205 or 222 with a low psi turbo - it's still going to be slow without upgrades. If you want real performance then start with a built 257 short block with forged internals. 205 heads, manifold, and ECU will be fine. We have 02-05 WRX's making 400 WHP on 205 heads with 257 block/ cams @ 25 psi.

GD

#10 monkeyposeur

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Posted 21 August 2017 - 11:53 PM

Hybrids are a good way to go for sure. I get 350 whp out of my 22T/205 with a  20gxt on 91 oct @ 4250 ft. (03 WRX). The WRX swap/merge route is nice because you can actually tune the damn thing. But if you are just in it for fun you can get away with a lot.

 

If you want to boost your 22E with your stock I would source some 22T heads. You can pick of a set for next to nothing on bbslegacycentral. I've thrown out three sets of 22T heads because no one ever wanted them. Or find some 22 dual ports. But if you don't care if anything blows up try the 25d heads. One of the problems with mating 2.5 heads to a 2.2 block is you end up with a mushroom like bore/combustion chamber combo which causes heat issues and detonation, but if you're running low boost it probably isn't a huge problem.

 

22Es are actually pretty solid blocks. The sleeves are thicker than 205 and 257 sleeves. The open deck isn't really an issue if you aren't going for mad HP.


Edited by monkeyposeur, 21 August 2017 - 11:54 PM.


#11 86BRATMAN

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Posted 22 August 2017 - 05:57 AM

The mushroom chamber only happens with 96 25d heads. 97-99 25d have the same chamber as the ej20k and late ej20g.

#12 monkeyposeur

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Posted 22 October 2017 - 11:01 PM

^If you use STi 257 2.5 heads you will also get the mushroom chamber. Thanks for the clarification though.



#13 86BRATMAN

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Posted 23 October 2017 - 06:16 AM

Correct, but the ej255 D25 heads are fine on a ej22 shortblock. Their chambers are just shy of 97mm at their widest point

The ej22e does not have thicker sleeves than the ej205 though. The 205 is 10mm and the ej22e is 8.5mm.





Also tagged with one or more of these keywords: ej22, ej25, legacy, 1999 legacy, WRX, frankenmotor

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