Re: [alfa] RE: Fuel Economy vs. RPM

["The Baylys" <dabaylys@xxxxxxxxxxxxxx>]

Ben,

I believe when the guys say "Full Throttle" they don't mean foot flat to the
floor per se.  The term is theoretical and rarely as simple in real life.

Think of full throttle as the single throat of one carb (say a Weber) with
the butterfly removed, engine running at max torque RPM, and no other
'stuff' connected.  Effectively a wide open straight tube with no
restrictions, and theoretically producing zero manifold vacuum (OK lets say
manifold pressure at ambient).  This system isn't 'choked'.

The fact that the system when fitted to a vehicle in real time doubles the
injector cycles, adds excess fuel or whatever, is irrelevant to the THEORY.
Of course it mean a boatload in reality.

But then I own a Duetto so my reality is likely different to others !!!

Beatle
Oz
----- Original Message ----- 
From: "Ben Dorfan" <ndorfan@domain.elided>
To: <alfa-digest@domain.elided>
Sent: Friday, May 14, 2004 8:20 AM
Subject: [alfa] RE: Fuel Economy vs. RPM


> I was reading Pat Braden's AR owner's bible and I found something that
> might ressurect the fuel economy vs. RPM discussion. This was in a
> previous post on the subject:
> //
>
> Date: Sun, 02 May 2004 10:07:52 -0600
> From: C M Smith <cmsmith@domain.elided>
> Subject: [alfa] Fuel economy and rpm
>
> When BMW introduced the 528 e (the e standing for Eta, a Greek letter
> having something to do with thermodynamics I believe) they did so while
> advertising the results of their fuel economy testing which established
> that you should drive a gasoline powered car as close to wide open
throttle
> as possible, at as low rpm as could be used to do the job (i e accelerate
> the car) then cruise at the desired speed with the throttle as open as you
> can without accelerating the car. In other words, the old jack rabbit
start
> so pooh poohed by the so called experts was proved to be most efficient...
> //
>
> For cars equipped with Bosch Jetronic EFI, full open throttle triggers
> the full-throttle switch that activates what Braden describes as a
> "damn-the-torpedoes mode. (pg 48)" The injectors fire twice (instead of
> once) per 4 revolutions, and the oxygen sensor reading is ignored,
> allowing a richer than normal mixture. This leads me to believe that,
> while close to wide open throttle (as described above) may be most
> efficient, "floored" full throttle throws economy out the window.
>
> Ben
> 87 Spider
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