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Old 04-21-2004, 05:42 PM   #1
2.5racer
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Default sti bottom end

so heres the thing... I'm not planning on doing anything untill I pay off my car at the end of the summer, but I was looking at some options for some more power. First came the thought of turboing my rs.... then I thought about a wrx swap... then I thought I'd rather have a j-spec sti version 3 now I'm wondering about something.
I think I heard of a few people doing a build up useing the sti shortblock on 2.5rs heads then useing like a ludespeed turbo kit and blam a reliable 15+psi engine that has TORQUE (with engine management and fuel mods) does that sound right?
is there more than... parden my french... slapping the 2.5rs heads on the bottom end of the sti block... I'd probably get some other things while I was at it like stronger valves and springs, maybe turbo cams... anyhow you get my drift ... as bare minimum for the block and heads will they work together?
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Old 04-21-2004, 05:45 PM   #2
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I have this swap on my 00RS. Everything bolts right up, as if it were "meant to be". It is true that you can run 15psi on this motor with the right fuel, and management etc..
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Old 04-21-2004, 05:48 PM   #3
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thank you god..... I'm so glad to see people have tried this.... how do you like the setup? and how much did it cost you (I can do all the labor, and I have access to my dads shop with lifts, all tools etc.)
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Old 04-21-2004, 06:14 PM   #4
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when you do the STi block do you have to do pistons too crank or anything with it? If not what kind of CR are you running stock RS pistons and STi block?
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Old 04-21-2004, 07:21 PM   #5
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the sti shortblock already comes assembled so you dont have to do any of that stuff. already has, pistons, crank, etc.

i think people are getting around 8.0 CR with SOHC heads, at least i know thats what graham got with his cometic gaskets and hybrid.
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Old 04-21-2004, 08:12 PM   #6
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Quote:
Originally posted by PHATsuby
the sti shortblock already comes assembled so you dont have to do any of that stuff. already has, pistons, crank, etc.

i think people are getting around 8.0 CR with SOHC heads, at least i know thats what graham got with his cometic gaskets and hybrid.
Has anyone tried this with the 98 DOHC heads yet?
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Old 04-21-2004, 08:12 PM   #7
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The setup is awesome you get the whole package for 1400 instead of 3000 if you were to peice everything out your self.I have 8.0 compression as stated above.
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Old 04-21-2004, 09:11 PM   #8
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spend the extra money and get the big port and polished dohc sti RA heads. Your motor and turbo will thank you.

Then u can go past 6200 rpms too
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Old 04-21-2004, 11:38 PM   #9
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that crank and piston's are cast correct? semi closed block and everything will work on both phase I and phase II engines?
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Old 04-22-2004, 12:20 AM   #10
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yes..
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Old 04-22-2004, 01:13 AM   #11
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man this is sounding great.... pi what part of colorado are you in... cause I'll be in colorado from saturday the 24th untill friday the 30th... I'm going out there to get my subie back from my brother... long story... I'd love to stop by and see your setup... and maybe get a ride in it.... i'll be in lakewood the whole time but i'll drive a ways to see that setup.... plus I have to go north to get back to oregon anyways....
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Old 04-22-2004, 02:20 AM   #12
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Quote:
Originally posted by ImprezaRSfan!
spend the extra money and get the big port and polished dohc sti RA heads. Your motor and turbo will thank you.

Then u can go past 6200 rpms too

It is my understanding that the SOHC ports are even larger than the DOHC, and still outflow even the RA heads.

Graham is revving to 7k with no problems so far on stock heads.

if you wanted to be totally sure then spend another 600 and do cams and springs and retainers, 7k with no worries there.

Ben

Last edited by PHATsuby; 04-22-2004 at 02:26 AM.
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Old 04-22-2004, 12:16 PM   #13
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What actually determins your red line though? Head's, cams, or ECU? Ecu i'm assuming is the actual thing that cuts the power and going over the Rev limit can damage parts. so on the stock heads won't that hurt something? 6250 stock RS rev and i would love 7Grand rev so i could pull 3rd to 90 just like a W or close to it.
-Eli
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Old 04-22-2004, 12:19 PM   #14
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ecu determines the point. It basically just cuts fuel off at this point. I don't know of any electronics that will just increase the redline, but I do know that you have the ability to do this with a stand alone...Im sure you knew that.
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Old 04-22-2004, 12:21 PM   #15
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Does any know the CFM for the RA heads?
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Old 04-22-2004, 05:06 PM   #16
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most software lets you set the redline
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Old 04-22-2004, 05:19 PM   #17
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Quote:
Originally posted by squirrelmasta
Ecu i'm assuming is the actual thing that cuts the power and going over the Rev limit can damage parts. so on the stock heads won't that hurt something?
This is kinda hard to answer, it really depends why the redline was set at 6250. if there was problems with rods breaking by reving higher then the head might be fine to who knows what rpm.

i have also heard that the stock engine loses power over that rpm anyway, so maybe its just set there because the stock engine cant perform well above that.

like PHATsuby said, throw in a couple hundred dollars more to rebuild the head and you should be good. you would probably want to do that no matter what if your car has any kind of high mileage (dont know how many times the car has made the Colorado-Oregon trip ).
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Old 04-22-2004, 06:23 PM   #18
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Quote:
Originally posted by NeaD
Has anyone tried this with the 98 DOHC heads yet?
Marc Rameriz, aka Xephyr is running that set up. He has had it in for a couple months now. He doesn't post here to much anymore, but is around on occasion. He was one of the first to use the EJ22T block, along with Joe Cox. Check in the Proven Power or the RMIC forums and you will see details on his 381whp dyno run.
According to Marc, he is sold on the EJ257 shortblock, and just finished selling off his EJ22T blocks and is starting to build another EJ257 based engine...
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Old 04-22-2004, 06:30 PM   #19
Matt Monson
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Quote:
Originally posted by PHATsuby
Graham is revving to 7k with no problems so far on stock heads.

No he's not. He took Marc's advice and upgraded the springs. The limiting factor on both the DOHC and SOHC EJ25 heads is spring tension. Above 6500rpm or so you get valve float. There is no need to port these heads. There is no need to replace the cams. Just spend the money on springs and retainers and call it done. As I said above, Marc hit 381Whp on an EJ257 bottom end with DOHC EJ254 heads with just a spring upgrade. He has a set of ported heads he has used, but prefers the unported ones because they come on power a little earlier and provide a flatter power curve. The ported heads are more peaky...
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Old 04-22-2004, 07:02 PM   #20
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the car has made 1 trip from oregon to colorado this time last year... now it's comeing home and this buildup is sounding better and better.... how much were the valves springs and retainers?
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