Date:         Tue, 15 Oct 2002 16:29:56 -0400
Reply-To:     David Brodbeck <gull@CYBERSPACE.ORG>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Brodbeck <gull@CYBERSPACE.ORG>
Subject:      Re: Turbo Diesel Power and Economy Comments/ Gasoline Too
Comments: To: Frank Grunthaner <FrankGRUN@AOL.COM>
In-Reply-To:  <24.2d27ecda.2add9228@aol.com>
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Tue, 15 Oct 2002, Frank Grunthaner wrote:

> In any case, the numbers for the 1.6L 4-cyl TD and the 2.0L 5-cyl TD are 264
> and 261 grams per kilowatt hour. Please note that the 5 cyl engine with 20%
> larger displacement (swept volume) actually uses less fuel to produce the
> same amount of power as the 4-cyl design. Both measurements were taken at 6
> Bar boost pressure and 1800 rpm. Clearly the 5 cylinder engine is the more
> efficient design. It produces more power in total than the 4 cylinder design
> while consuming less fuel per unit power developed.
>
> My point in raising this is just to point out that larger engines do not
> consume more fuel ... the fuel used is related directly to the work done (or
> requested as it were).

I'm not sure that would hold if you did the comparison between two gas
engines instead of between two diesels.

What's the difference?  The throttle plate.  Diesels don't have one.

If you have a small gas engine and a larger gas engine producing the same
horsepower output, the larger engine will be at a smaller throttle
opening.  That means a higher manifold vacuum, and more energy lost
pulling air through the smaller opening.

             _ _
  __ _ _   _| | |  | David M. Brodbeck (N8SRE)              Ypsilanti, MI
 / _` | | | | | |  +-----------------------------------------------------
| (_| | |_| | | | @ cyberspace.org
 \__, |\__,_|_|_| "I think the brilliant aspect of the Bush speech last
 |___/             night is that it was crafted so simply that even Bush
                   himself could understand it." -- Leeron Kopelman