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Discussion Starter #1
Due to a broken WRX engine i am thinking about doing the STI bottom end with my WRX heads:) Everthing i am seeing is saying the STI bottom end is a direct swap. I need a new oil pump pick up timing belt set. Is this stuff the same for the WRX & STI?? also will the header i have of my 2.0 now fit with the STI bottom end or is the STI block wider and i now need new header?? Same with the intake?? Will my stock WRX one fit or do i now need an STI one?? If anyone had done this swap any info or help would be great THANK:thumbup:
 

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Ok.. So yes the STi swap is a direct fit. You will need the Wrx oil pan or a different oil pan. Everything else will work just fine. You will need to be re-tuned however.
 

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Everything will bolt right on.

HOWEVER, two issues arise. First off, your compression ratio rises, and that's not necessarily good. Best to ask your tuner what he suggests, but it likely will involve thicker headgaskets, or perhaps some machining. Secondly, you NEED a tune. You will NOT be okay temporarily without one. Talk to a tuner BEFORE the build to help you out.
 

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That's only one issue.. Compression is different resulting in needing a new tune.
 

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Discussion Starter #5
the car already has a tune in it now for the mods that are already done. I already have 850cc injectors and a 255pump. while the heads are off i was prob going to change the cams also. So it will deff need retuned. A raise in compression is prob not going to be good runnig 20lbs of boos now. The closest AWD dyno and tuner that i trust is about 2hours away so it will deff need to be towed. Am i good with just a start up to make sure everything is ok??
 

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your tuner should be able to set you up with a base map so you can load it on to the car with a tactrix or cobb ap and run that thru its break in.. Honestly a 2.5 bottom end is a good start but if you build the 2.0 or do a 2.2 your gonna be just as good in the end. if not better being more reliable with a built motor.. STi bottom ends have a slightly better piston but still not amazing..
 

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Discussion Starter #7
That's what I was not sure about building my 2.0 too a 2.2 or putting a STI 2.5 in it. I hear pusses and
Minus both ways. This is not a race car this is my DD car it will drive in Ohio snow and prob see 15k-20k miles a year. When I got the car it already had a Perrin front mount inveden downpipe FP green turbo 850cc injectors. I
Just want to use what came on the car to its potential yet keep myself from
Blowing up the motor.
 

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Build the bottom end. Unless you want to keep going thru oem short blocks.
 

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Discussion Starter #9
i was thinking about a 93mm bore 70mm stroke that should put me at about 2.15L and staying around 8.3-8.5 compression. Arp head studs. Is stock subi bearing good or should i go aftermarket. I am also looking at the crower 222/400 stage 2 cams. It would be sweet if i got this thing up to about 400WHP!!
 

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Discussion Starter #11
based on the 400Hp post i have about 90% of that stuff. my car hit 320whp with 22lbs of boost this summer.MY goal is to make this car just as fast as my LS1 car which does 480WHP. I dont mind falling short of the 400mark. There is plenty of EVO's in my area that is at the 350-400 mark and i would love to run with a few of them out of a WRX not a STI :)
 

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For that much power? I'd definitely build the bottom end even if you use the 2.5. Plus 2.5 headgaskets ARP headstuds, CNC work to the heads, and expect it to blow up sooner or later.
 

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Discussion Starter #13
i am leaning to doing STI bottom end with new pistons and total seal gapless rings. I already have arp head studs in a box for the build. I just need to know of a good head gasket. I have cometic on my LS1 but i have heard a few not so good things about them on the SUBARU engines?
 

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There's so many things to go wrong with a subaru engine, I used cometic and haven't had an issue but that's not to say others won't. The best way to not rebuild a scoob every year is to leave it stock.
 
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