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hey eveyone. i have been doing some research since i bought my stag a few months ago and ive come to the conclussion that there is alot of wrong information. i would just like to point out the 1 major point that puts everyones information possibly wrong.

what ive found

1st bit of info - 700 millimeter of mercury [0 °C] = 13.535 744 51 pound/square inch (converion program)

2nd bit of info - top line of guage(+700mmHg) is 9psi (info found on here)

3rd bit of info - my guage reads the half way line at 8psi (testing with a boost guage in my car)

4th bit of info - with boost control unplugged reads 1/4 of guage at 5psi(testing with boost guage in my car)

so is the info found on here incorrect or are the other 3 incorrect?? is the factory boost guage wrong in my car??

im not trying to make anyone look silly, i would just like to know the truth. sorry if anyone is offended.

thank you, i look forward to the replies

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https://www.sau.com.au/forums/topic/233017-series-2-factory-boost-guage/
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check where the vacume line goes onto the factory boost gauge sensor . its quite random plastic and mine had split and the gauge was just generally up to f all . its on the same bracket that holds the throttle cable right where ti comes through the fire wall . the pipe is on the bottom . i now get full range of movement on factory gauge . nearly -700 and right through to +700 which is what my defi gaugeg says -600 to 0.7kgf/cm2 . +700 mmHg and 0.7kgf/cm2 both equal ten psi . well they did on the pressure converter i used .

Edited by lachlanw

700mmHg is NOT 9psi. It IS 13.5psi.

Your factory guage was likely not made to be super accurate or entirely linear in response.

The factory guage is a guide and should not be used to accurately monitor boost.

For instance my zero (atmosphere) is about 2mm below the zero on my guage, and it can vary a little in it's response day to day.

Edited by simpletool

ok my bad i swear it did last time i checked . meh good thing i have the defi gauge aswell . not that it really matters besause my car is only gonna have ten psi up it which it came from the factory with . mmHg is a vacume measurement anyway . stupid unit to measure pressure with . the r34 gtt factory gauge is in kpa .

ok my bad i swear it did last time i checked . meh good thing i have the defi gauge aswell . not that it really matters besause my car is only gonna have ten psi up it which it came from the factory with . mmHg is a vacume measurement anyway . stupid unit to measure pressure with . the r34 gtt factory gauge is in kpa .

I think bar is the apprporiate measurement. I have just changed my psi boost gauge for one that reads in bar

100kpa=1 bar (=14.5psi)

and I plan to run my Series I at 0.8bar until I get a new turbo.

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