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Old 12-15-2004, 02:37 AM   #1
Scooby Guru
Member#: 64673
Join Date: Jun 2004
Chapter/Region: NWIC
Location: portland
1990 Legacy wagon
goes 12.387 @ 116.5

Default What % of hp increase per psi of boost?

Is thre any way to figure this? Obviously low compression motors equal smaller % gains, but can go way up in PSI boost levels, while high compression motors have much bigger gain per psi, but cant climb as high without serious problems.

I am just trying to guestimate my hp at this stage, boosting the 2.2 1990 motor which has 9.5-1 compression, 6 psi at this stage, hopefully 8-9 psi by the time I dyno test this spring.

I normally estimate an increase of 7% per psi but this is for motors set up for boost, ie low compression motors. Just wondering if high compression motors give a noticeable increase % per psi of boost.
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Old 12-15-2004, 03:32 AM   #2
Scooby Specialist
Member#: 49958
Join Date: Dec 2003
Location: in your mom's pants...and MN
'03 Cobra DSG


One main thing you need to remember is that PSI is just how much pressure of air is being pushed, not the amount. I think that CFM would have a much greater effect. Without knowing CFM of the air (volume), you really couldn't get a good figure.
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Old 12-16-2004, 02:15 AM   #3
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Member#: 36333
Join Date: May 2003
Chapter/Region: NESIC
Location: East Kingston NH
98 RS
GT30R, closed deck madnes


yea its really wierd...when someone asks you how much boost you are running, it means absolutly nothing. A vf22 running 15 lbs of boost is going to be a hell of alot more HP than a td04 (stock wrx turbo) running 20.
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Old 12-16-2004, 03:58 AM   #4
Scooby Specialist
Member#: 73471
Join Date: Oct 2004
Chapter/Region: SCIC
Location: socal
2004 WRX Stg2+some
Blk melon launcher


lil advice: get somebody knows how to tune it, before u break it
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Old 12-16-2004, 04:02 AM   #5
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Member#: 25516
Join Date: Oct 2002
Chapter/Region: NWIC
Location: Send help, stuck in internet!
1995 Legacy TURBO!!!
EJ22T/TEC3 & '12 Civic


Hey red,

I was wondering if you had a picture of your injectors out of the car. I am still trying to compare the n/a reds to the turbo pinks.


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