MAF and Calculated VE

[nacelp]

You make some of this sound so easy <g>....

Rho=Manifold Air Density  (g/litre)
How does one calculate that?.
Thanks
Grumpy

========================================================================
> Here's a formula that should work:
>         VE = m_dot / ( N * Vol * Rho / 120 ) * 100
> where:          VE - volumetric efficiency (%)
>                 m_dot - mass air flow (g/s)
>                 N - crank speed (rpm)
>                 Vol - Engine Displacement (litres)
>                 Rho - Manifold Air Density (g/litre)
> where:          Rho = 1.202 * MAP / 101.325
>                 MAP = Manifold Absolute Pressure (kPa)
> You should also compensate the air density for temperature too since
> the 1.202 is air density at 20_C and inlet temperature is elevated due
> to heat transfer from the manifold surfaces etc.
> Also VE for family cars these days will probably be better than 80%.
 ========================================================================
 Notice that if you know airflow (MAF), you can calculate VE.  But you
> still have to have confidence in the ECM sensor numbers for air density.
> Right now, the next move may be to install the 3300 MAF code, and see
> if the MAF is reading correctly, that is, does it run right using
> the MAF data.  If the MAF data is good then I will see if the calculated
> VE numbers make any sense, as compared to those determined using O2
> feedback.  
> Thanks, Scot Sealander


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