Date: Fri, 18 Oct 2002 09:20:56 -0500
Reply-To: John Rodgers <j_rodgers@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <j_rodgers@CHARTER.NET>
Subject: Re: Increasing horsepower
Content-Type: text/plain; charset=us-ascii
Turbo Charger, Electro Charger, Turbine Compressor......!
The principle is the same. A turbine (turbo) takes in air, and using
centrifugal force compresses the air which exits the compressor into the
airflow system of the engine. Thus the charge of air for the fuel is
more dense, and there fore needs more fuel for proper fuel/air ratio.
Greater amount of fuel/air into the cylinder means more power for the
same displacement.
How that turbine is driven is not important except from an efficiency
standpoint. Exhaust drive is the most convenient and probably the most
efficient as it provides some power recovery from the heat and motion
energy of the exhaust.
The shop where I have been working has a high pressure air compressor
that is a centrifugal turbine type compressor that uses an electric
motor to drive it.
Today, automotive application of electric drive turbo compressors may be
reasonable, given changes in technolgy.
There are two approaches as to the goal of turbo charging or
supercharging as it were. Ad it applies heavily to piston powered
airplanes particularly.
One, to turbo charge for the purposes of INCREASING horsepower, and two,
to turbocharge for the purpose of MAINTAINING horsepower as altitude
increases. In the case of the latter, automatic flow gates are installed
so and overboost won't occur with the resulting engine damage such as a
blown cylinder --- literally - right off the engine. Automotive engines
apparently are stout enough to handle a certain amount of boost to get a
horsepower increase without damage.
My 2 cents.
John Rodgers
88 GL Driver
John Rodgers
88 GL Driver
Andrew Grebneff wrote:
>
> >Superchargers are normally powered from the main crank (which means
> >that they add more air in proportion to the engine speed.)
>
> In fact most superchargers today are exhaust-driven, and are sloppily
> called turbos. This has been a thread on the list before. Turbos ARE
> superchhargers, plain and simple. They came into common use on
> American aircraft in the war (B17s, B24s, LP38s) and were initially
> called "turbosupercharger", later contracted to "turbocharger".
>
> >However,
> >with modern electronics, yah, I guess it is possible to add them and
> >control them via electronics (and electric motors) instead. I can see
> >certain advantages to that too, like no additional friction added to
> >the crank...
>
> VW had Mitsubishi working on electric turbochargers in the 80s, using
> torpedo-motor technology. This came to nothing, obviously, or these
> would have replaced exhaust-driven turbos (allow me a little
> hypocrisy!).
>
> Note that a turbocharger MUST have a turbine, or naturally it's not a
> turbo. A turbocharger has an exhaust-driven turbine connected by a
> shaft to a compressor wheel. As an electric unit would have no
> turbine (replaced by a motor), it would not correctly be a
> turbocharger. So what should it be properly called? Ideas?
> Electrocharger? Bah, just electric supercharger.
> --
> Andrew Grebneff
> 165 Evans St, Dunedin 9001, New Zealand
> <andrew.grebneff@stonebow.otago.ac.nz>
> Seashell, Macintosh, VW/Toyota van nut
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