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Old 01-21-2005, 08:18 PM   #1
WRC1
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Join Date: Nov 2003
Location: Los Angeles, Ca/Madison, Wi
Vehicle:
2000 Impreza 2.5 RS
Blue Ridge Pearl

Default STi short block with Phase II 2.5RS heads?

I am planning on changing my RS motor to a forced induction and i wanna run high boost (around 20-24psi) So Im planning on buying an EJ257 short block but im not sure what heads i should use.

My question is can I just use my heads from my phase II RS engine (SOHC MY00 2.5RS)? Also can i use the intake manifold off my RS engine and put it onto the STi short block? How about the oil pan? Fuel rails with different injecters(Im think not enough fuel will get to the engine with the stock rails?All the stuff that is attached to front of the engine (AC comp., alternator, etc.)?

Sorry for all the questions but Im a n00b with engine builds.

Thanks
~Leor
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Old 01-21-2005, 08:33 PM   #2
scoobydorift
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yep everything should bolt up just fine.
Rick
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Old 01-21-2005, 08:36 PM   #3
WRC1
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I was pretty sure that everything would but my main concern is the heads not flowing enough air and it being SOHC rather then DOHC.

Will the Phase II heads flow enough air to support 22 psi?

~Leor
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Old 01-21-2005, 10:56 PM   #4
Notfastenough
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i believe ther was a post about this before... that the sohc heads will flow around the same amout. *i could be wrong*
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Old 01-22-2005, 03:37 AM   #5
IdenityCrisis
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the sohc hads actually flow more than the dohc heads. myoo rs heads were tested by cob awhile back and out flowed a paire dof ls1 heads. i'm in the middle of a sti sb swap, and i'm using my myoo rs heads with some nice cames and forged pistons. - IC
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Old 01-22-2005, 03:48 AM   #6
WRC1
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If i do end up using my RS heads will i need to buy better springs and cams or can i run it stock until i gather enough money to do the rest.

~Leor
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Old 01-22-2005, 04:35 AM   #7
speed_freak27
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2.5>2.2T>257>2.35S

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I'm in the process of doing a swap right now I'm using an ej22 leg motor with sohc heads. You will need to at the very least upgrade your valve springs and retainers or you will get valve float with higher boost. If you want to run 20-24 I would also reccomend upgrading to forged pistons while your doing it. As far as intake i would start searching for a 99 intake manifold because no one makes injectors for the 2.5 manifold with air assist anymore. The 99 manifold will accept any wrx injectors. I've got some rc440 cc injectors for sale for the 2.5 but with that amount of boost you'll more than likely need something larger. Everything else will bolt up though no problem with exception of the intake manifold/injector issue. I would do ALOT of searching and reading before you decide to do this yourself it's a lot of work and can get very expensive. I'm pretty close to about 5-6k right now and that's without the upgraded tranny and I've already got engine managment and turbo kit. Hope this helps out if you need any ?'s answered shoot me a pm.
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Old 01-22-2005, 04:23 PM   #8
WRC1
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Thanks speed_freak that helps a lot but I always thought that any wrx injectors can fit into any 2.5RS guess but then again I dont know to much about power mods.

~Leor
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Old 01-23-2005, 01:20 AM   #9
speed_freak27
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No problem and I found out about the injector issue the hard way I had to spend about 500 for a new 99 manifold from subaru. One other thing you should make sure to get the right impedance injectors for whatever engine management you are going to run. Most run high imp but will run low's with a resistor pack.
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