Re: cheap power

[QSHIPQ@aol.com]

In a message dated 97-05-09 14:58:41 EDT, you write:

<< > The air flap is drawn open by vacuum, ...
 
 No, it's forced open by flow.  The chamber into which it moves is very 
 carefully shaped - in effect, it defines the mechanical enrichment curve.
 
 The problem comes with density - if the air moving past the plate is more
dense 
 than the curve (chamber shape) was designed for, you will mis-align the 
 fuel/air volume curves.
 
 --
  Phil Payne
  phil@sievers.com
  Committee Member, UK Audi [ur-]quattro Owners Club
  >>
Really the same thing said two ways.  And both correct.
I suppose we could really nerd into this for a while.  The difference in flow
is created by vacuum (motor demand - variable, the point), specifically the
the "flow" of air at atmosphere trying to equalizing the pressure on both
sides of the flap, raising it as the inequality of the pressure raises in a
tuned cone.  Atmospheric pressure is a constant (the point) in a CIS system.
 Since atmosphere is a constant, differential of flow is not "technically"
created by pressure but changing vacuum (motor air demand), maybe <0 bar
"pressure," but again we can nerd this to the hilt.   A flow of air, thru a
given "cone" will create a fuel demand curve that can be "tuned" for a
specific motor by cone dia and pitch.  Air pressure IS air density by
definition in the case of "ram air".  So not sure the same thing isn't being
said two different ways, I will always take a technical explanation of proper
terminology, however, given the issue for discussion, not sure the technical
explanation isn't more confusing.  

The same conclusion, by Phil's "terminology" or mine, is that ram air gives
you an incorrect, in fact mostly rich, fuel condition, because you are
changing the constant by which the flap and cone shape were designed to
deliver fuel = atmospheric pressure (k) vs. vacuum vs. cone pitch and
diameter.  Ram air by definition, is above atmospheric pressure, changing a
constant in an equation that will give you rich fuel throughout the operating
range of the flap.  Not good.

HTH

Scott