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From: moroney@jon.DEC (Mike Moroney)
Newsgroups: net.auto.tech
Subject: Re: Turbos and superchargers
Message-ID: <715@decwrl.DEC.COM>
Date: Sun, 26-Jan-86 00:43:11 EST
Article-I.D.: decwrl.715
Posted: Sun Jan 26 00:43:11 1986
Date-Received: Sun, 26-Jan-86 20:15:46 EST
Sender: daemon@decwrl.DEC.COM
Organization: Digital Equipment Corporation
Lines: 35


Turbochargers and superchargers do the same thing, they compress air to force
more air/fuel mixture into the cylinders to get more power.  The basic
difference in automotive language is where the devices get their power. 
Turbochargers get their power from a turbine in the exhaust system, powered by
exhaust pressure.  Superchargers (often called "blowers" by racing types) are
belt-driven, like the alternator, water pump, etc.

Advantages to Turbochargers:

1) Use "free" power (exhaust power)
2) Physically smaller, since the device uses higher RPM's (as much as 100K)

Disadvantages:

1) Turbo "lag" between the time you step on it and the turbo kicks in
2) Non-linear function of throttle position and power (many people with turbo's
   love this, though)
3) Potentially unreliable, because of the high temperature from exhaust + high
   RPM's (they are pretty good now, however)
4) Not too useful at low RPM's


Supercharger advantages:

1) Linear power response, like a bigger motor
2) No turbo "lag"

Disadvantages:

1) Uses motor power
2) Can be large (racers often have them sticking through the hood)

-Mike Moroney
..decvax!decwrl!rhea!jon!moroney