Superchargers are not necessarily positive-displacement. A supercharger
is just any kind of mechanical device for stuffing more air into the
engine than it could normally inhale. Superchargers are either:
- driven off the drive shaft of the engine they are enhancing
- driven by a turbine spun by the exhaust gasses of the engine, in which
case it is a turbo-supercharger, or just turbocharger
- driven by a completely separate engine (I believe some research
aircraft of the 30s used this)
It may well be that most engine-driven superchargers for automobile
engines are PD pumps, but centrifugal superchargers do exist. Most
high-performance aircraft piston engines use centrifugal superchargers.
The only difference between a supercharger and a turbocharger is in the
manner in which they are driven.
Blower is just a colloquial term for a supercharger.
> -----Original Message-----
> From: Jerry Causey [SMTP:reecau@whidbey.com]
> Sent: Tuesday 6 January 1998 16:26
> To: mgs@autox.team.net
> Subject: Re: Supercharged LBC
>
> > Mike Lishego wrote:
> > >
> > > I hate to show my general automotive ignorance, but can someone
> explain to me the
> > > difference between superchargers, blowers,and turbo units?
> Supercharges are positive displacement air pumps. They pump a
> particular
> quantity of air into the engine for every revolution they turn, so the
> effect
> is noticeable at every point in the engine's RPM range. The boost
> pressure
> remains more or less constant across the engine's entire RPM range. A
> blower is
> an Americanism for a supercharger. A turbo is a pair of fans
> (turbines) mounted
> on a common shaft. One sits in the exhaust stream and is spun by the
> exhaust
> pumped out by the engine. The other fan sits in the intake stream and
> pushs air
> into the engine. The faster the engine spins, the faster the turbo
> spins, and
> the larger the volume of air pushed into the engine. Generally
> speaking, turbo
> boost increases as engine RPMs increase.
>
> Regards,
> Jerry Causey
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