engine

acemyles2.5i · 08-09-2009, 08:04 PM

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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anothernord · 08-10-2009, 12:26 AM

You want to lower the compression ratio to allow more boost to be used. Either a thicker headgasket or just turbo pistons/rod/crank.

acemyles2.5i · 08-10-2009, 05:23 PM

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

Tradewind · 08-10-2009, 07:42 PM

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

jey · 08-13-2009, 10:51 AM

Another option: a beefier preassembled block already exists. The EJ257 STi block bolts right up to your heads.

Harenil · 08-13-2009, 11:43 AM

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.

PA-Outback2000 · 08-13-2009, 11:44 AM

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?

subiidude · 08-13-2009, 02:44 PM

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

SUBYAWD85 · 08-14-2009, 01:14 PM

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.

VIsubi · 08-15-2009, 08:38 AM

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..

koester95 · 08-15-2009, 07:13 PM

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).

08-09-2009, 08:04 PM	#1
acemyles2.5i Scooby Specialist Member#: 151012 Join Date: Jun 2007 Chapter/Region: South East Location: lakeland, Fl Vehicle: 2007 impreza 2.5i urban	engine 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 * Registered users of the site do not see these ads.

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08-10-2009, 12:26 AM	#2
anothernord Scooby Newbie Member#: 193703 Join Date: Nov 2008 Chapter/Region: RMIC	You want to lower the compression ratio to allow more boost to be used. Either a thicker headgasket or just turbo pistons/rod/crank.

08-10-2009, 05:23 PM	#3
acemyles2.5i Scooby Specialist Member#: 151012 Join Date: Jun 2007 Chapter/Region: South East Location: lakeland, Fl Vehicle: 2007 impreza 2.5i urban	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

08-10-2009, 07:42 PM	#4
Tradewind Scooby Newbie Member#: 159312 Join Date: Sep 2007 Chapter/Region: International Location: Australia Vehicle: 2005 Subaru Impreza Aqua Blue	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

08-13-2009, 10:51 AM	#5
jey Scooby Specialist Member#: 32503 Join Date: Feb 2003 Chapter/Region: TXIC Location: Johnson City, TX Vehicle: 2011 Tribeca 1995 Legacy Wagon	Another option: a beefier preassembled block already exists. The EJ257 STi block bolts right up to your heads.

08-13-2009, 11:43 AM	#6
Harenil Scooby Newbie Member#: 93071 Join Date: Aug 2005 Chapter/Region: RMIC Location: Golden, CO Vehicle: 1995 Impreza L EJ22G (Hybrid EJ22T/EG20G)	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.

08-13-2009, 11:44 AM	#7
PA-Outback2000 Scooby Specialist Member#: 161832 Join Date: Oct 2007 Chapter/Region: Tri-State Location: PA Vehicle: 2000 Outback Limited Black	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?

08-13-2009, 02:44 PM	#8
subiidude Scooby Newbie Member#: 141472 Join Date: Feb 2007 Chapter/Region: MAIC Location: moco Vehicle: 2008 shagg wgn STI OG FP20g+e85 corn booze	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

08-14-2009, 01:14 PM	#9
SUBYAWD85 Scooby Newbie Member#: 208228 Join Date: Apr 2009 Chapter/Region: SCIC Location: Oceanside, CA Vehicle: 2007 Impreza 2.5i Newport Blue	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.

08-15-2009, 08:38 AM	#10
VIsubi Scooby Specialist Member#: 187834 Join Date: Aug 2008 Vehicle: 06 2.5i impreza Red	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..

08-15-2009, 07:13 PM	#11
koester95 Scooby Newbie Member#: 219059 Join Date: Aug 2009	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).