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----- Original Message ----- From: "Jim Adney" <jadney@vwtype3.org> > > On 12/5/2003 Jim Adney wrote: > > > Hmmm.... Would this also be the correct relationship between pressure drop > > > across the intake venturi and airflow thru it? > > > > Yes. The relationship (Bernoulli's Equation if you're interested) holds for > > a venturi too. > > I had a chance to think about this a bit more over the weekend and finally > realized that we don't really care how the pressure drop across the venturi > goes. It's still the pressure in the intake air distributor that is feeding the > cylinders, and that is what the PS is measuring. I think you would still want to consider where in the air distributor that the measurement is being taken.At the "mouth" of the distibutor the velocity would be greatest=high vac.Further in ,velocity would drop=lower vac.I believe that the port is centered where the air takes the turn into the runners.Move the port rearward(back to the rear of the car)=richer mixture and vice- versa. > > So I still think an appropriate adjustment would be to increase the fuel > pressure in proportion to the increase in displacement. This would be a linear > approximation to the actual engne needs, which would be correct except for the > non-linearity in the pressure drop between the IAD and the cylinder. Don't think there's a shoulder in there.Should be linear enough. <Porting > the heads somewhat, should actually compensate for that latter effect somewhat. Hmm.... "....the whole world , Chico. And everything in it." David V. Nelson 1969 Fastback FI (no matter what!) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org