Don Stauffer wrote:
> Alex Rodriguez wrote:
> > In article .com>,
> > says...
> >
> >
> >>I thought a supercharger was demand based, i.e. not running at light
> >>throttle openings
> >
> >
> > No, that more accurately describes a turbocharger. Until you get enough
> > exhaust gas flow, it is basically doing nothing. To get more exhaust gas
> > flow, you need to step on the throtle some more.
> >
> > -----------------
> > Alex
> >
> Centrifugal gear driven superchargers also had very little boost at low
> rpm. Positive displacement ones such as Roots and the GMC style gave
> boost at all rpm.
>
> There were also some engine driven chargers that had a complicated drive
> mechanism that did respond to throttle position in terms of speed of
> charger. These were for street machines. I think there was a clutch
> that either kicked in, or speeded up the blower speed on higher throttle
> openings.

The old centrifugal McCullochs (later Paxton) used a variable ratio
drive pulley.

http://www.vs57.com/

nate