Never really paid too much atten to vacuum pressure. I have an RS w/the same gauge. If you dont get an answer ill have to check this weekend

Thank you👍

Took this pic today & was at 900-1K on the idle. Engine was not warm

https://cimg0.ibsrv.net/gimg/www.evo...30c6509579.jpg

Mines sits at the same spot as the one in the picture.

That converts to 16.5 in/Hg.. conversion factor is cm/Hg / 2.54 = in HG

When cold @fast idle the car will show about that and then when hot very close to 20 in HG. Mine does the same.... Timing drives it. When cold the ECU uses 5 degrees of timing and then once warmed up it uses 10 degrees or whatever is on the HO timing map at that rpm.

-30 seems like way too much

I have cams so I get -18 psi of vacuum.

I got -14 to -16 on my s1s and -8 to -12 on my s2 but I asked for it very lopey lol

I didnt realize it was CM/HG seems pretty normal than.

Nice. The power band must feel great up top :thumbup:

My stock guage reads the same. Even though my map sensor sees less then -10 at idle. " Gsc S2".

It's because it's a metric gauge.
Look at the scale, it pegs out at 76 which is cm of Hg where a "normal" imperial gauge is in units of inches Hg (pegs out at 30ish).
76cm is close to 30 inches.

Normally you'd expect a vac reading of 18 to 20 inches (2/3 of an atmosphere) at idle. That would be about 50cm on that gauge.

as said above.

If it's reading zero at idle, it's because it's hooked up wrong. As in hooked up to the intake pipe before the throttle body.

Yeah I noticed after that it was metric, but thanks!