butterfly valves

[Gary Derian]

An engine creates a much higher vacuum behind a nearly closed throttle than
a nearly open one.  This greatly aggravates the non-linearity of the flow.
A variable linkage to slow down the throttle angle change per pedal movement
when nearly closed would help.  There are many techniques to do this.  Some
auto makers make the linkage do the opposite to make a car feel faster.  To
calculate flow against a constant vacuum, a close approximation could be
made by measuring or calculating the effective area of the opening.

Gary Derian <gderian at oh.verio.com>
>
>  Does anyone have a typical chart of flow vs. valve angle for round
> butterfly valves?  I thought this would be something I could look up in
> my shelf of engineering handbooks, but I've come up with nothing useful.
>
>  I expect the flow would be highly nonlinear; I'm just trying to come up
> with a rough table to start off with for a delta-TPS injection setup.
>