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Old 09-03-2009, 05:06 PM   #1
subydude02
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Question can i use an outback 2.5l short block and put sti internals in it???

Alright guys i got a question here for the community. I have a friend of mine that just pulled the motor on a 2001 outback. He works from home as a mechanic, and this was one of his customers cars. The customer just decided to pic up a cheap used motor for his outback, from what he told me the existing motor had a blown head gasket and some other minor things wrong with it. I have an 02 bugeye and plan on putting a 2.5 sti short block with my wrx heads in it in the future. My question is can i build the short block of this 2.5L outback motor with sti internals? Would it even be worth it? Also are there differences between the sti short block and the outback short block, just the shell itself, substantial enough to make it not work? He said he'd sell it to me for the core charge from where he bought the new motor that he put in, 60 bucks! So even if it doesn't work for building it then maybe i should just buy it and tear it apart for the experience?? Let me know what you guys think. I appreciate it

-Caleb Huxster
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Old 09-03-2009, 05:41 PM   #2
john 1badSTI
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The blocks are interchangeable to a point I think the outback block is open deck where the sti block is semi-closed deck.
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Old 09-03-2009, 06:02 PM   #3
kpluiten
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+1, the N/A 2.5 does not have much of the reinforcements of the EJ255/EJ257 block. You can do it, but I wouldn't waste my time. I've seen blown EJ255's and EJ257's go for $400, maybe less.
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Old 09-03-2009, 09:52 PM   #4
reddevil
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I am currently pushing 22 psi on an NA opend deck block, bored to 100mm for Mahle pistons with STI rodss. About 350 whp?
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Old 09-04-2009, 12:25 AM   #5
subydude02
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i was kinda wondering about the reinforcements of the block and how it would hold up endurance wise with much more positive pressure and mush more strain on everything as a whole as it is a N/A block like you mentioned. i guess i'll have to do some more research on open vs semi closed vs closed deck. seen it mentioned alot and get the impression the closed deck is "the best" but i don't fully understand the differences.

reddevil- are you currently running that motor right now or in the process of building it? i'd be interested in more details of your setup!

Thanks all for your help
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Old 09-04-2009, 01:45 AM   #6
reddevil
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2.5 NA block unknown year
100mm Mahles
NA crank I think
STI rods
twinturbo heads
Borla header with custom up and down pipes, 2 1/2 and 3" exhaust
NA intake manifold
800cc sidefeed injectors
Blow through Modded JECS MAF
EBAY T3/T4 turbo
BigAss FMIC

Dyno sheet for 15 psi.. Now hitting 22 psi or so in 4th and 5th gears....



I have made 400 whp on an phase 1 block as well, but due to advanced timing, lost pistons a few times in that one.

Not saying the NA block is the best, just that is can be done reliably.
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Old 09-05-2009, 07:13 AM   #7
domestic_abuser
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Quote:
Originally Posted by john 1badSTI View Post
The blocks are interchangeable to a point I think the outback block is open deck where the sti block is semi-closed deck.
This is the only real difference, besides the heads. That really doesn't matter though since your doing a hybrid build. You could buy the block and have a closed deck plate machined for it anyways, that's what I'd do.

On the other hand don't use STi pistons, the rods though can be had rather cheap and are good for like 500whp or some **** like that. It's just worth the money to buy some forged pistons though. You'd have a built 2.5L for like $800 if that.
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Old 09-06-2009, 01:27 PM   #8
subydude02
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thats a really good idea, never thought about that with getting some plates machined to make it a closed deck. and good idea on forged pistions. might as well seeing as i'll prob never have the motor torn down that much again. Thanks! sound slike i'm gonna grab this motor regardless and slowly work on it as i get the funding! anyone else that has any other ideas or experiance plese still post up!

Thanks
-Caleb Huxster
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Old 10-01-2009, 01:02 PM   #9
subydude02
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bump!
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Old 10-01-2009, 09:48 PM   #10
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Quote:
Originally Posted by subydude02 View Post
Alright guys i got a question here for the community. I have a friend of mine that just pulled the motor on a 2001 outback. He works from home as a mechanic, and this was one of his customers cars. The customer just decided to pic up a cheap used motor for his outback, from what he told me the existing motor had a blown head gasket and some other minor things wrong with it. I have an 02 bugeye and plan on putting a 2.5 sti short block with my wrx heads in it in the future. My question is can i build the short block of this 2.5L outback motor with sti internals? Would it even be worth it? Also are there differences between the sti short block and the outback short block, just the shell itself, substantial enough to make it not work? He said he'd sell it to me for the core charge from where he bought the new motor that he put in, 60 bucks! So even if it doesn't work for building it then maybe i should just buy it and tear it apart for the experience?? Let me know what you guys think. I appreciate it

-Caleb Huxster
The STI rods and pistons will drop right into the block for a very inexpensive shortblock. Most companys like us have hundreds of new STI pistons and rods laying around looking for a good home

Team Crawford
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Old 10-01-2009, 10:01 PM   #11
Texy32
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You can send the block to outfront motorsports and they will close deck it for $800 dollars. If you are not looking for more than 400hp You can go with STI rods but I would run forged pistons. The USDM oem Subaru pistons are junk. I have rebuilt at least 12 motors because the piston ringlands cracked.

The only other difference in the blocks besides the semi closed is the EJ257 has an extra crankcase breather in the middle top of the right block half. You can tap the NA block and put a breather there. I have done it before on a EJ205 that I put a STI crank into.
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Old 10-05-2009, 12:27 AM   #12
subydude02
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hmm that sounds like a good route to get a fully closed deck. i def know know that i'll go with forged internals instead of oem one now after your suggestion and added research. actually going to go the route of destroking the 2.5 block by putting in my stock 2.0L wrx crank
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Old 10-05-2009, 05:22 PM   #13
subydude02
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bump!
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Old 10-26-2009, 12:50 AM   #14
subydude02
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bump!
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Old 10-26-2009, 02:50 AM   #15
FuJi K
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Quote:
Originally Posted by subydude02 View Post
actually going to go the route of destroking the 2.5 block by putting in my stock 2.0L wrx crank
so...what are you waiting for??
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Old 11-19-2009, 09:33 AM   #16
subydude02
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money, i'm getting married in 6 months
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