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Old 23 Aug 2010, 02:28 PM   #1 (permalink)
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WRX to STI Conversion

Quick questions, im looking at putting an sti v8 onwards engine in my bug eye, as im going for big power and want the sti engine as a startin point. I know i need sti ecu and key transponder to match the engine, my question is do i need anything else to go with these things, I am hopefully going to buy a rear ended sti so i have a full car but we all know how many of these pop up for sale so its not always possible so if i have to buy just parts i need to know what i need. Also what needs to be from same car etc as in ecu transponder engine all from same doner car,

Thanks in advance
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Old 24 Aug 2010, 04:02 PM   #2 (permalink)
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Re: WRX to STI Conversion

define "big power".
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Old 24 Aug 2010, 06:15 PM   #3 (permalink)
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Re: WRX to STI Conversion

Might be handier to buy an sti with all the parts already on it
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Old 24 Aug 2010, 08:26 PM   #4 (permalink)
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Re: WRX to STI Conversion

With how much it will cost might be cheaper to sell the WRX and buy an STi, more money for modding then
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Old 25 Aug 2010, 12:30 AM   #5 (permalink)
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Re: WRX to STI Conversion

ive already spend 2k on the car since buying it for 4k, looking back yes a sti would be cheaper lol but id only get 4k back for mine so a 2k loss straight away, so id rather carry on with what ive started, im in no rush so il wait till what i needs engine ecu wise comes up at the right money,hopefullly a rear ended sti write off, and pwer wise im aiming for 450 bhp
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Old 25 Aug 2010, 07:24 AM   #6 (permalink)
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Re: WRX to STI Conversion

a standard sti8 bottom end will take 450bhp.

One problem you may have is if you are planning on using your existing heads, the STi8 heads have vvct which require additional wiring.
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Old 25 Aug 2010, 08:28 AM   #7 (permalink)
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Re: WRX to STI Conversion

just get an sc450, job done
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Old 25 Aug 2010, 11:31 AM   #8 (permalink)
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Re: WRX to STI Conversion

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a standard sti8 bottom end will take 450bhp.

One problem you may have is if you are planning on using your existing heads, the STi8 heads have vvct which require additional wiring.
Yeah i need the engine bay loom with the ecu (thats what duncan told me when he mapped it)
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Old 25 Aug 2010, 11:34 AM   #9 (permalink)
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Re: WRX to STI Conversion

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just get an sc450, job done
To be honest dont want a car built by somebody else and i can do the same quality build myself for way less money. Yeah it would be easier but way less fun and i wouldnt be able to say id built it myself. I just need to do my research and make sure i know about anything that could be a problem so im well prepared when i start it.
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Old 25 Aug 2010, 11:44 AM   #10 (permalink)
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Re: WRX to STI Conversion

ah right i get ya.

tbh ej257 block, rods, pistons, heads, supporting mods and supporting turbo will prob be the best route, responce and reliability wise for road use up to 450bhp.

after that the block starts to get a bit risky.
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Old 25 Aug 2010, 12:35 PM   #11 (permalink)
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Re: WRX to STI Conversion

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ah right i get ya.

tbh ej257 block, rods, pistons, heads, supporting mods and supporting turbo will prob be the best route, responce and reliability wise for road use up to 450bhp.

after that the block starts to get a bit risky.
Well if it means reliablitly may be sacrificed at 450bhp id be happy with about 400bhp to 425bhp, if it meant its less likely to go bang.

and dummy question again here tidge but im assuming ej257 block is the later 2.5 one, i was thinking about this as well, but i was wanting the vvct heads so will need sti ecu and engine loom as well iirc. along with countless other things lol.
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Old 25 Aug 2010, 03:54 PM   #12 (permalink)
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Re: WRX to STI Conversion

drop in an sti8 complete engine, with the right turbo and ancilliaries will get you 450bhp.
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Old 25 Aug 2010, 04:18 PM   #13 (permalink)
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Re: WRX to STI Conversion

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drop in an sti8 complete engine, with the right turbo and ancilliaries will get you 450bhp.
what internals does these sti8 lumps have, i was wanting to put forges pistons etc in as i want a strong engine, although dont sti ones have them already, and before the laughing im full of silly questions lol. Ive been saving them for years
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Old 26 Aug 2010, 08:09 AM   #14 (permalink)
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Re: WRX to STI Conversion

the standard sti (2002 to 2004) are forged, mine has been running at 450bhp for 3 years now.

If you are going to strip it, you could put aftermarket pistons in for future proofing.

But if you are going to the trouble of changing pistons, as long as you have a strong block (semi closed or fully closed) it wont matter what age of car it comes from.
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Old 26 Aug 2010, 09:23 AM   #15 (permalink)
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Re: WRX to STI Conversion

cheers JD, I am going to buy a 2002-2004 sti block then and build from there,
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