FC3S Murray's never ending build.

[MaczPayne]

Originally Posted by FC3S Murray

Shit my boost controller reads -15 now at idle. Max, yours is -7.3 at partial throttle then??

is -15 in inches of mercury? It cannot be psi since complete vacuum on earth is -14.5psi. My idle is -7.3psi, or -15 in Hg

Originally Posted by TitaniumTT

I understand what you're saying. Basically need to reference out the difference between mani pressure and atmosphere right?

So then, how would one go about getting the "standard" "hg from a kpa reading? I know there is a descrepancy between my Motec and autometer gauge. But when the Motec reads 50 kpa, the AM says ~14-15"hg. 10 kpa = ~25"hg. So, how does one go about converting the kpa reading to the standard "hg?

What units does the Motec show when you are in boost? Is it still kpa? Does the kpa value decrease when you open the throttle?

If the reading is kpa in boost:
The Motec most likely references absolute pressure. So all you have to do is a simple subtraction. Atmospheric pressure is 14.5psi, or 100kpa. Since the Motec reads 50kpa at idle, 100kpa(atmospheric) - 50kpa(gauge) = 50kpa (your vacuum), which is also equal to 14.764" Hg. Pretty smack dab where your AM reads!