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Old 04-16-2013, 10:44 PM   #1
Scooby Newbie
Member#: 291992
Join Date: Aug 2011
Chapter/Region: Tri-State
Location: Virginia
2006 Wrx ej257
Rally blue

Default How much power with my swap?

So I just swapped my 06 Wrx engine for an 06 ej257. And my main question is how much power should I expect to be making with the following mods: ej257, sti intercooler, rfl bov, vf39 that likes to push 25 psi in 3,4,5 (I gotta fix this I know), aem ebc, 8mm spacers, gates racing belts, lightweight perrin pully, turbo inlet pipe, short ram intake, stock sti headers and up pipe, 4 inch clear down pipe, 3 inch mid pipe, Perrin dual tube out the rear, 255 pump, 750 dw injectors, open source tune from precision (tuned for Wrx engine). Obviously I'm going to have to do something about this 5 speed glass box and get a tune. But I'm just curious at what power the car is making with these mods since its going to be months till I'm able to hit the dyno. Anyone have a ball park figure? Thanks.
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Old 04-18-2013, 03:33 PM   #2
Scooby Newbie
Member#: 351592
Join Date: Mar 2013
Chapter/Region: International
Location: Ottawa, ON
1999 RSTI Ver. 6


Honestly, not much more than stock. Till you get a tune though, no one can really just tell you what you'll be making. BOV will just shorten the **** out of your turbo and 25 psi on your bone stock internals isn't going to make your engine last for very long. Most of the mods listed are for prepping your engine for future internal upgrades. Like DW injectors, 255lph FP, spacers, belt, pully, intake, stock sti ****, etc... isn't honestly going to do **** for power. It'll help your engine for the future, but no power gains.
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Old 04-18-2013, 03:46 PM   #3
Dave D.
NASIOC Supporter
Member#: 130990
Join Date: Nov 2006
Chapter/Region: NWIC
Location: Menzel Lake, WA
06 Red Ltd.Wagon
Dom 1.5xtr JJ tuned


The same mods on an EJ255 vs. a 257 will yield virtually identical numbers.

The heads have different chambering, and I've heard said the 257 heads might be good for a little more tq. But nothing significant.
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Old 04-18-2013, 04:04 PM   #4
FuJi K
Scooby Guru
Member#: 3687
Join Date: Jan 2001
Chapter/Region: MWSOC
Location: St. Paul, MN
MY99 GF4 JDM 6spd
NF Performance


Whatever STi's make with bolt-ons is what you'll make. It's a vf39....
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Old 04-20-2013, 04:32 PM   #5
Scooby Specialist
Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
2001 Forester STI


With proper tune, your looking at probably around 285hp and 300 torque on a mustang dyno. As for 25psi, your wasting your time on pump gas. After 21psi, those smaller turbos are past their efficiency and blowing hot-air into the motor and not making more power. With hot air coming in like that, it will increase your chances of knocking and the ecu (hopefully) pulling timing.

Your best bet is to run a lower boost, say, 19 psi, allowing a more aggressive use of timing advance to give you that initial thrust feeling of torque as boost kicks in.
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