Which Gauge Reading Should I Be Reading

[djvoodoo]

My Greddy Profec B II and aftermarket boost gauge read about 1.5psi in difference (on RB25det Neo).

Greddy is tapped into the boost pressure sensor- reads hi of 11.2

Boostgauge is tapped into one of the vacuum lines on the inlet manifold (kinda near the AAC screw)- reads 12.5

Should I be trusting the reading from the Greddy rather than the aftermarket gauge? As most people suggest, trying not to put more than 11.5psi through the Neo turbo.

[DVS JEZ]

Is it a cheap gauge? Does it sit perfectly on 0 when the cars off

[djvoodoo]

Is it a cheap gauge? Does it sit perfectly on 0 when the cars off

It's a fairly cheap gauge, "Drift" branded, so one of the ones you can pick up at Autobarn etc etc (was on the car when I bought it). It does sit perfectly on 0 when off. I'm still leaning towards referencing the Greddy though

[l0WRB]

thats barely a difference to be worrying about regardless.

[Harey]

Really? 1.5 psi sounds like a fair difference to me.

One idea is to switch where each gets its boost signal from and see what happens. If they swap around then its the place your getting the signal from, if they stay the same one of them is dodgy etc.

[l0WRB]

he mite not be looking at the gauge from the right angle and even from that pov it could read 1psi either way.. like lookin at your fuel gauge from the passenger seat, always looks like its got more in it unless ur looking at it direct front on , so 1.5psi on a boost gauge could mean he isnt even lookin at it directly front on without any sense of angle on it! id go from your profect b reading.