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Date:         Sat, 19 Oct 2002 01:01:13 +0100
Reply-To:     Clive Smith <clive.harman-smith@NTLWORLD.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Clive Smith <clive.harman-smith@NTLWORLD.COM>
Subject:      Re: Increasing horsepower
Comments: To: John Rodgers <j_rodgers@CHARTER.NET>
Content-Type: text/plain; charset="iso-8859-1"

>Automotive engines apparently are stout enough to handle > a certain amount of boost to get a >horsepower increase without damage.

So are aero engines, a racing Merlin can take maybe 120-140" boost, thats 3 to 4 atmospheres! Mot many auto engines get near that! In fact it maybe takes 1000 hp to drive the superchargers!

Clive

----- Original Message ----- From: "John Rodgers" <j_rodgers@CHARTER.NET> To: <vanagon@GERRY.VANAGON.COM> Sent: Friday, October 18, 2002 3:20 PM Subject: Re: Increasing horsepower

> 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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