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Old 08-09-2009, 08:04 PM   #1
acemyles2.5i
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whats a good writeup that breaks down the boxer engine, specifically the 06-07 series, im looking to go boost on mine considering a swap is out of my range, and i can get the parts for the setup for fairly cheap, but i know theres alot more than just slapping on a turbo kit, i want to know what exactly needs to be replaced to handle about 10psi or so, ive been talking about it with a mechanic friend of mine and hes positive i could do it by beefing up the block and running low boost, but i want the specifics....thanks
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Old 08-10-2009, 12:26 AM   #2
anothernord
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You want to lower the compression ratio to allow more boost to be used. Either a thicker headgasket or just turbo pistons/rod/crank.
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Old 08-10-2009, 05:23 PM   #3
acemyles2.5i
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well i was gonna go with wrx rods, piston and crank, but wasnt sure if they will just swap over, im thinking of just buying a manual for my car and reading up the differences between mine and the same year (06-07) wrx, i was thinking of doing a complete swap, but then again i was gonna see if i could run low boost, but the horror stories on here scare the living **** out of me haha im not the richest guy but i got some money to do this project, but only once lol im just kind of stuck, more reading for now i guess though....thnx
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Old 08-10-2009, 07:42 PM   #4
Tradewind
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Run the right SC/ECU and you can go up to 6psi with no horror stories at all.

There could be a 3-4psi kit coming out for your model which bolts right on and gets you going
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Old 08-13-2009, 10:51 AM   #5
jey
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Another option: a beefier preassembled block already exists. The EJ257 STi block bolts right up to your heads.
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Old 08-13-2009, 11:43 AM   #6
Harenil
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Another option - I have to suggest this. Sell the 2.5i and get a WRX.

Otherwise, I agree with jey, EJ257 would be a definite good bet, that way you could run a significant amount of boost with little risk.
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Old 08-13-2009, 11:44 AM   #7
PA-Outback2000
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for 10psi, like Jey said, u need a stronger block and lower compression pistons. stock, u can do 6psi no problem, but u need a new/piggy-back ECU and someone that can tune the car well so it won't blow up. AVO has a kit that bolts onto the 2.5L engine. how much do u want to spend?
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Old 08-13-2009, 02:44 PM   #8
subiidude
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the crank in the 2.5 i/rs is the same as the sti, only need sti rods and pistons to make it sufficiently beefy
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Old 08-14-2009, 01:14 PM   #9
SUBYAWD85
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AVO is designing a kit right now that will run 6psi safely. It will bolt up to the 06-07 2.5 engine with running stock internals. If you beef up the internals with forged pistons, etc, you can probably run more.
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Old 08-15-2009, 08:38 AM   #10
VIsubi
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OK people whats wrong with you....to do 10 psi you would need a good tune and stock internals can do it..theres a guy on here that ran 10 psi all day the nwent to 14 psi on a lagacy only to blow up the motor due to experimentation on the tune at 14 psi... the WRX pistons aren't even forged neither are the USDM STI pistons on that year 06-07 hawk eye there silica treated..all you would need is pistons the rods on the 2.5i are already forged shared by the wrx rods and like stated all three share the same crank which is also forged...so to answer your question some forged pistons of the same compression ratio 10:1 with that 10 psi of boost to make the same power a wrx would need to run 4-5 more psi of pressure...I tell everyone that low compression pistons are very much overated and just make your turbo work more at spooling up or half that with big power. Yes your heads can handle 350 hp to the wheels. Maybe add some stronger head gaskets not so much to lower the compression..
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Old 08-15-2009, 07:13 PM   #11
koester95
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Hey, I have put a turbo kit on my 07 2.5i. Its runs good outside of WOT. I have it external gated at 4 psi. Outside WOT, it will hit 3 psi, but at WOT it only do 1 psi. I was thinking it was going lean, so i got an FMU 12:1. Now the problem is that it when it hits 1 psi, the car dies. I have to crank and crank to get it to start again. I'm thinking it is going into fuel shutoff if it has that, but not sure. Any ideas? Any help would be nice. And by the way I have less than 800 dollars in my kit and I installed it my self (cert. tech, 26 hours to install with my factory cats still in it).
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