On several occasions I have tried to make sense of the PFC pressure scale without any luck. Can someone please tell me what unit the pfc measures abs pressure in is so I can come up with a conversion constant to go from PFC units to PSI, Bar, KG/CM^2 ect.

A forum member logged pressure with the pfc and a couple different boost gauges at the same time. I tried to find a conversion constant by dividing the abs pressure unit by psi. Unfortunately the constant changes as boost increases. I believe this is because abs pressure is 1 ATM+ any pressure above it. As the pressure above 1 atm increases ATM becomes a smaller component of the total, in turn causing the conversion factor to shift. However, because I don't know what unit the pfc measures in I can't 'zero' the scale by subtracting 1 atm from the abs p value.

psi abs p abs per psi
10 16629 1662.90
14 19205 1371.79
16 20517 1282.31
18 21855 1214.17

 

Absolute pressure on the PFC is in kilogram-force/square meter (kg/m²), not to be confused with kg/cm².

 

Now to makes things worse; as boost increases, the PFC boost value becomes less accurate! It reads PIM voltage correctly but when comverting to ABS and then tp Kg/Ccm^2 is messes up.

 

skotx,

That hit the spot thanks.

Chuck,

I saw your post on the datalogit forum about the accuracy issue. Thanks for recording the different boost readings. It obviously took a bit of time to do, but I and others have really benefited from it.