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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.auto.tech
Subject: Re: Turbos and superchargers
Message-ID: <740@kitty.UUCP>
Date: Wed, 22-Jan-86 16:53:19 EST
Article-I.D.: kitty.740
Posted: Wed Jan 22 16:53:19 1986
Date-Received: Sun, 26-Jan-86 05:34:19 EST
References: <2763@sunybcs.UUCP>
Distribution: net
Organization: Recognition Research Corp., Clarence, NY
Lines: 38

>    I think i might have an idea, but I am not sure.  Could someone please 
> post a condensed explaination of the difference between turbochargers and
> superchargers?  What are the advantages of one over the other?

	The amount of fuel-air mixture which is introduced into an internal
combustion engine PER CYCLE is generally referring to as a ``charge''.  A
``supercharger'' by definition is any device  which increases the amount of
charge per cycle above that of a normally aspirated engine.
	While a supercharger can be anyone of several types of air compression
devices, the term ``supercharger'' seems only to be applied to application of
such devices to internal combustion engines; i.e., the same air compression
device used for another application may simply be called a turbocompressor,
rotary vane compressor, rotary blade compressor, etc.
	From what I can gather, a ``turbocharger'' is a turbocompressor applied
as a supercharger.
	A compressor used as a supercharger can be powered by three means:
(1) direct coupled to the engine, (2) powered by a close-coupled exhaust-driven
turbine, and (3) powered by an electric motor with speed control.  Compressors
used in (1) and (3) are low speed (i.e., << 5000 RPM), whereas devices used in
(2) are high speed (i.e., >> 5000 RPM).
	Since turbine technology results in the smallest possible size for a
compressor, it is the most common device used in passenger vehicles.  Since
turbines require higher RPM's than can be conveniently achieved by direct
coupling to the engine, and since a turbine MOTOR as powered by engine
exhaust gases can generate the required RPM's, the combination of an exhaust-
driven turbine motor close-coupled to a turbocompressor is most commonly used
in passenger vehicles.  I believe most people refer to this device when using
the term ``turbocharger''.
	However, while ``supercharger'' is a precise engineering term, this
may not be the case for ``turbocharger'' - even though the two terms are often
used synonymously.

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