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EJ25 heads


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7 replies to this topic

#1 Matty B

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Posted 31 May 2006 - 01:45 AM

How do SOHC EJ25 heads stack up with regards to reliability.
Verses the EJ22.

I am looking for a compression drop head swap for the next monster.

#2 970subaru

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Posted 31 May 2006 - 03:21 AM

I am actually building an ej22e block/sohc ej25 head motor right now as well.
reliability should be fine.
flow will be MUCH better.
you will have a variety of options for a forced induction friendly CR.
SOHC or DOHC heads, SOHC is bigger combustion chamber.
use either SOHC or DOHC ej25 headgaskets, get the metal ones.
the SOHC are thinner, DOHC are thicker. you can get 8.3:1 with SOHC heads and a DOHC gasket, thats what I am doing. thats the lower of the combos you can get with the ej22e block and pistons. I may put some ej22t pistons in that motor for 7.6:1, not sure yet.

since you are down under, look at getting some ej20k or ej20g heads from a wrx, they have amazing flow and will lower your CR as well, though I do not know by how much.
play around with the numbers on here:
http://wac.addr.com/...bo/ejcalcs.html

#3 Matty B

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Posted 31 May 2006 - 07:13 PM

Thanks 970, that is exactly what I needed to hear!
I have to go with SOHC as I have clearance between my frame rails (just).
DOHC heads will not fit.

They are the compreession numbers I wanted to see. PERFECT for 10psi.
Keep in touch and let me know how your creation goes.
Cheers,
Matt

#4 svxpert

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Posted 31 May 2006 - 09:45 PM

<<970subaru I am actually building an ej22e block/sohc ej25 head motor right now as well.
reliability should be fine.>>



what size head gaskets are you mating to your 2.2 block? the 2.5 ones or the 2.2 ones?

Thanks 970, that is exactly what I needed to hear!
I have to go with SOHC as I have clearance between my frame rails (just).
DOHC heads will not fit.

they should fit on any legacy or impreza. there wasn't much of a size difference in the SOHC and the DOHC heads.


#5 970subaru

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Posted 01 June 2006 - 12:38 AM

you must use the ej25 head gaskets, the ej22 ones will not match the water passages of the ej25 heads.
you can use either variety of ej25 gasket, one is thin one is thick, to suit your CR.

the clearance issue matty is talking about is because the motor is going in his brat. to tell the truth I have no idea on the size difference, though the valve covers of the SOHC are prety low profile but I cant speak for the DOHC.

matty, so far the plan is to get the motor together, get it running on megasquirt, and build some forced induction in the form of either a garrett T3/T4 probably .63, or some sort of blower. I would like to fit a vortech V5 but they are kinda spendy. maybe I will build a manifold for an eaton M90 with the charger under the plenum.
but I am still in parts sourcing/rebuilding phase.

#6 Matty B

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Posted 05 June 2006 - 06:37 PM

maybe I will build a manifold for an eaton M90 with the charger under the plenum.
but I am still in parts sourcing/rebuilding phase.


Spectacular plan!
Thanks again for the info.
Big thick DOHC gaskets, SOHC heads, 20% bigger crank pulley!
Hopefully it should stay reliable now.

#7 ballitch

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Posted 05 June 2006 - 10:04 PM

i would reccommend using this gasket 11044aa610, its the new design 4 layer MLS gasket for the DOHC EJ25. you can push 15 psi through that block/head combo as long as you have a decent/good tune on it. 20 psi is were it breaks. at least 10 psi for good fun/driveability/mileage. remember, you will need the EJ25 intake manifold for this combo, heads need to match intake manifold, IIRC. should be fun....


~Josh~

#8 Matty B

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Posted 05 June 2006 - 10:14 PM

Josh,
I was just ordering, sensational.
thanks for the part number.


Cheers.
Matt.




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