Date:         Fri, 23 Jun 2006 13:02:39 -0700
Reply-To:     John Bange <jbange@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Bange <jbange@GMAIL.COM>
Subject:      Re: ? for our mechanical wizards
In-Reply-To:  <449C3970.7020303@charter.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 6/23/06, John Rodgers <inua@charter.net> wrote:
>
> Can anyone tell me what the flow rate of intake air - cubic feet per
> minute - is on the WBX 2.1 L engine ...and.... for one cylinder .... say
> at top rpm and/or horsepower?
>
> Also, what is the cylinder volume of air taken into the engine on a
> single intake stroke?


Well, to answer your second question first, I bet each cylinder pulls in
about 525 cubic centimeters per intake stroke. From that I'd hazard a guess
that at 4500rpm  you're sucking 4725 liters of air per minute? (4500rpm *
2.1liters / 2 revs per intake stroke)

And finally - anyone have any opinions on this concept......"Improved
> vaporization of fuel will improve gas mileage!"


There is truth to that, but it doesn't matter as much as it sounds like it
should. When the fuel comes out of the injector and hits the 100degC+ head
and intake valve, it vaporizes about as well as it possibly can. Some
argument can be made that there are schemes that would improve vaporization
when the engine is cold, when the fuel has a tendency to condense on the
cool metal parts, but optimizing for the first five minutes of engine run
time is something of a waste of effort. So far, every "trick" I've seen
offered that claims "better fuel vaporization" has been shown to produce
nothing beyond a fatter wallet for the seller. The best way to improve
mileage is to drive slower and not press the gas pedal down so far. The
gross inefficiencies of gasoline engines, particularly the good ol'
wasserboxer, are pretty much beyond the reach of chemical tweaks like
acetone. Amusingly, a sheet metal intake choke (aka a "Turbonator") will
actually improve gas mileage, but only by reducing max airflow, essentially
doing the same as not pressing down the accelerator as far.

--
John Bange
'90 Vanagon - "Geldsauger"