VE tuning on 3.8 jeep

[tjhenne]

I am trying to wrap my head around tuning the 2 VE tables on on 2011 Jeep wrangler 3.8. The axis on the VE table is RPM vs Ratio. What is this ratio? is it equivilance ratio? I am used to the LSX platform and am lost here.

I am logging manifold pressure (kpa) RPM, wideband AFR ratio.

I have put a 1320 eaton blower on it and trying to get the VE correct prior to returning to spark tuning.

I have attached the file.

Any help is appreciated.

[B00STJUNKY]

Ratio is Pressure Ratio, and is a function of Manifold Absolute Pressure divided by Atmospheric Absolute Pressure.

So, at sea level where atmospheric pressure is 14.7:1, if you are running 14.7 psi of boost on the gauge (meaning 29.4 psi Absolute), your Pressure Ratio would be 2.0.

For me, where I am at 4500 ft elevation with an Atmospheric Absolute Pressure of 12.5 psi, if I were running 14.7 psi on the gauge (14.7 psi over my atmospheric pressure), my absolute pressure would be 14.7 psiG + 12.5 psiA = 27.2 psi Absolute in the manifold.

27.2 manifold absolute / 12.5 atmosphere = 2.18 Pressure Ratio.

[tjhenne]

Awww - Got it. So I will need to monitor it with a custom build PID then.