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Old 10-17-2003, 02:13 AM   #1
White 2.5rs
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Default say i wanted an sti shortblock...what heads could i use

i think im giving up on building my block so would the usdm wrx heads work? but wouldnt i have to port their faces off?

i need help w/ this i think i found a shortblock shipped to me for 1575 but i need heads w/ it I NEED HEAD well 2 i guess
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Last edited by White 2.5rs; 10-17-2003 at 02:40 AM.
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Old 10-17-2003, 04:52 AM   #2
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Use the EJ25 heads, you'll be fine for a good amount of power.

If you use the Ej20 USDM heads, you'll need to re-wire them, which is a much larger process than just using the existing EJ25 heads.


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Old 10-17-2003, 09:47 AM   #3
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just about any heads you have....

search for i-speeds thread on sti block info.. and there are some others
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Old 10-17-2003, 10:01 AM   #4
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wait guys what about the whole sohc to dohc thing?
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Old 10-17-2003, 10:15 AM   #5
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rs heads out flow wrx heads...
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Old 10-17-2003, 10:52 AM   #6
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ok but with the shortblock this is what i get <if i dont include it please tell me>

block
pistons
rods
crank
all seals



now, since its a DOHC engine, wouldnt the lifters be shorter than the SOHC?
also what about the acvs thing?


so confused and i need to find my shiz out quickly because my car is gonna get booted out of the shop
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Old 10-17-2003, 12:08 PM   #7
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come on people i neeeeeeeeeeeeeeeeeeed help
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Old 10-17-2003, 12:56 PM   #8
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A shortblock is just a shortblock - there's nothing about it that determines what type of heads it's "set up" for. From what little I've read, it appears that the SOHC stuff bolts up to the block just as easily as the DOHC stuff. Items like lifters and avcs are specific to the heads they are installed in. Since you're getting a shortblock, none of that matters.

Now, I'm not trying to imply that any head that'll bolt up will work fine. But EJ25 heads, WRX heads, and STi heads will all work pretty well and give you acceptable compression ratios, so it seems like it would make sense to use what you have.

Just a note of caution: If you're having trouble understanding how the parts of an engine bolt together, are you sure you're a good candidate for a motor buildup? Do you have someone to help you with this?

_Jeff
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Old 10-17-2003, 01:02 PM   #9
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yes my dads a mechanic hes helping me w/ the more complex things like taking apart the block and gauging the tolerences

i appreciate your help, so what youre saying is that even thought the sti block is DOHC my SOHC rs heads will work fine w/ it???
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Old 10-17-2003, 01:12 PM   #10
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and also since the block would be set up for dohc wouldnt there be a big hole somewhere in the block to allow the cams to sit properly?
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Old 10-17-2003, 01:45 PM   #11
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No, the cams sit in the head.
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Old 10-17-2003, 01:51 PM   #12
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Quote:
Originally posted by White 2.5rs
come on people i neeeeeeeeeeeeeeeeeeed help
First calm down...

second seach for the info its out there.....


Quote:
and also since the block would be set up for dohc wouldnt there be a big hole somewhere in the block to allow the cams to sit properly?
go to www.howstuffworks.com and do start doing some research...... on how a motor works and where parts are.
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Old 10-17-2003, 02:16 PM   #13
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alright thank you
i did go there and am having a hard time finding HO engine stuff

so will the sti block mate w/ALL my shlt tho? like exhaust manifold...all that good stuff?

the engine should be ripped out today so ill be reading the post on and off

i really appreciate you guys and your help w/ the idiot
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Old 10-17-2003, 02:31 PM   #14
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DO a search through this forum. I can't remember who here had an RS-T with a fried block that got an STi swapped in at the dealer. But he posted an update when he got it back. He mentioned having to machine off one small area, but otherwise no problems. If you can find that thread it should reassure you that you can do this swap no problemo.

And your stock exhaust manifold will be usable, but I assume you know you need an up-pipe and a turbo... Sorry to flame, I couldn't resist. You do seem to be in a little over your head and should maybe slow down and do a lot of research and reading before you go any further. Just because the block is sitting on your floor doesn't mean it must go in the car today. I know a guy who has a block, tranny and cams on his floor and he isn't building for 6 months. Do it right and do it once...good luck
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Old 10-17-2003, 03:11 PM   #15
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A good place to start for general Subaru engine info would be to get a Haynes manual for a late '90's Legacy. I don't think they make an Impreza-specific one, or at least they didn't when I looked, but a huge portion of the content still applies.

Go through the engine section and look at the diagrams and pictures. This should give you a good idea of how the parts are laid out. To reiterate, there is no such thing as a DOHC "block". The block doesn't have any cams in it, so how could it possibly be DOHC or SOHC?? The cams are in the heads. If this isn't totally obvious to you, you really gotta take some more time and become more familiar with engines in general, and Subaru ones specificially.

I'm not trying to rip you apart, it's just clear you have no clue how your motor works. I'm afraid you're setting yourself up for an expensive disaster.

_Jeff
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Old 10-17-2003, 03:24 PM   #16
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thanks

i know ill need up/down pipes im not that stupid

but as far as knowing engines, im not entirely sure about some things but my dad was telling me some things that he wasnt sure about

ill search but so far no luck
thanks
alex
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Old 10-17-2003, 03:31 PM   #17
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A block is not "set up" for SOHC or DOHC. It can take either one. Yes, the USDM STi (actual car) comes with a DOHC head. But, this does not mean that can't use a SOHC RS head. You CAN use one, or you can use a DOHC RS head.



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Old 10-17-2003, 05:11 PM   #18
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White 2.5RS,
I think you know I was joking and not giving you the do a search nazi speil. I got bored at work and went looking on your behalf. Here's that thread...
http://forums.nasioc.com/forums/show...hreadid=423897

And now you are obligated to all of us to post pictures and updates as your build progresses.

EDIT: Fixed link. No longer about a DIY Cobb CAI MAF conversion

Last edited by Matt Monson; 10-17-2003 at 09:37 PM.
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Old 10-17-2003, 06:12 PM   #19
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i know i didnt think you were

well no pics but so far ive ripped all the stuff off the front and top of the engine, have to fix the ac <stupid ac core hole >

thanks guys i appreciate the help
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Old 10-18-2003, 02:37 AM   #20
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yea, i agree you should definitely research A LOT, before hand. even if your dad is a mechanic, im assuming not for subarus, and if that is the case, then he should definitely research too because subaru likes to be different with a lot of things, and it can be very frusterating. haha.

good luck with it though, should be sweet.

Ben
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Old 10-18-2003, 03:52 AM   #21
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Get boosted man!!!!


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Old 10-18-2003, 10:22 AM   #22
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well graham you did the block swap didnt you? <ej257>
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Old 10-18-2003, 02:08 PM   #23
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My STi block goes in next week. I'll let everyone know how its going.



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Old 10-18-2003, 03:04 PM   #24
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so what are u ending up using? the sti block obviously, but what heads did u decide on? in my oppinion, u should just use the 2.5rd heads u have on ur car now. unless u wanted to spend the extra money for dohc 2.5 heads. but its most likely not worth it.

Phil
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Old 10-19-2003, 09:24 AM   #25
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i guess this thread is all about reiteration... so i'll add in. Any ej series head can fit onto any ej series block. So.. a wrx head can fit onto a sti block, a rs block, jdm sti blocks, impreza L blocks, and it's vise-versa... but you'll have to have the additional parts such as mating intake manifold/exhaust manifold to mate up to the heads.

Please take your time... everyone knows they get ancy when a whole bunch of shiny parts are near them but if you do it right and methodical the first time you'll have tons more fun and less frustration let alone any "oops" bills..

goodluck though

Robert
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