Boost/turbo gauge

[ekalb]

Will someone explain this gauge to me like a drive around alone in my car with two masks on? Yes, I attempted to "RTFM".

I assume right of center that I am seeing the boost PSI, correct? 20 would be the max PSI on the right. What about 20 on the left side?

Whats going on left of center when the gauge is bouncing around? "in HG"?

 

[TurboM]

It means the engine/intake manifold is under vacuum (i.e. air is being pulling into the cylinders vs. forced in via boost)

 

[ekalb]

It means the engine/intake manifold is under vacuum (i.e. air is being pulling into the cylinders vs. forced in via boost)

thank you!!

 

[Vash]

@TurboM “in HG” is inches of mercury as opposed to PSI.