Testrun

So after my apexi pfc install I had about 1lbs boost creep according to the autometer gauge (analog).
she was around 8-8.5 psi.
I installed an AEM last night and was trying to compare the accuracy between the 2.
Apex .58 kg/cm2 on peak
Apex reads mmhg while running wtf
AEM .68 on peak in/hg
AEM PSI showing 9.9 psi

so what I assume is mmhg and kg/cm2 equal to be about the same?
why is nothing in life simple!!!???!!!!

Anyway, which would you guys trust more. The AEM hooked straight to line or the Apexi (commander) through ecu? Anyone else have different readings? Am I over analyzing everything? I dont plan on running over 11 on this current build so 1psi probably isnt a major catastrophe.





For one I am confused about kg/cm2

Testrun

Testrun

It is 91 heat index 101... damn it is hot down here.

DaleClark

iTrader: (55)

For boost, there are 3 standards that you typically see. PSI (pounds per square inch), BAR, and Kg/cm2 (kilograms per centimeter squared).

1 bar is 14.7psi, but 1 kg/cm2 is 14.2 psi.

Kg/cm2 is the "proper" metric unit for pressure.

Note that vacuum is in a different format - in the US you see inches which is inches of mercury, and in Japan they use mmHg which is millimeters of mercury. Basically it's how far mercury moves up a tube when sucked up by a vacuum.

That said the PowerFC has been shown to be not perfect in the calibration of its boost reading. It's close enough to do the job but it's not perfect. That's why at sea level it's not at zero, it's just below- the calibration is a little off. Chuck Westbrook has a method in his PowerFC for calibrating the MAP sensor.

Dale

Testrun

Thanks. I will check it out. I am going to go by the AEM as it is reading a bit higher and I will stay somewhat conservative for awhile.
Just before you responded I read about the vacuum in mmhg. Thanks for the reply.

BLUE TII

iTrader: (9)

Also, where the "vacuum" line is that leads to the boost sensor and how long the vacuum line is can affect the final reading.

Right off the turbo compressor will typically show the highest boost pressure and after the intercooler will typically show lower from pressure loss.

BUT a vacuum line off the intake manifold depending where it is at can show false peak pressure from the intake dynamic pulses (the inertial supercharging of the intake design).

I had MAP sensor line for Haltech on one of the FD UIM primary intake runner ports and it was showing spikes of 2-3psi on the map traces driving with the turbo removed. I switched the MAP sensor line to the plenum area on the UIM and it read a steady 0psi signal at WOT.

Testrun

Blue thanks so much. I just blindly hooked it to the line that fed the autometer. I will check to see the source and go from there. I appreciate your knowledge and time.

Terry