

| Subject: | Re: Fw: Re: ? for our mechanical wizards |
| From: | John Bange |
| Date: | Fri, 23 Jun 2006 13:43:03 -0700 |
> > > Assuming 100% volumetric efficiency, which no naturally-aspirated engine > > can have........... > > Well yeah, but we're already thrust almost completely in the dark as the the actual quantity of incoming air because we know the displaced volume, but not the temperature and pressure (P1V2T2=P2V1T1, and suchlike). The ECU uses TempI to get an idea of air temperature, and pressure integrates nicely with volume from deflection of the AFM vane well enough, but without access to any of the hard engineering numbers from the original VW flow bench tests they used to generate the ECU fuel map it's hard to say exactly how many pounds of air at STP are going through at any one time. I think all we can definitively say is that it's something less than 525cc of STP air per intake stroke (given that a NA engine runs a bit of a vacuum in the intake tract). -- John Bange '90 Vanagon - "Geldsauger"
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