[Diy_efi] sequential injection timing

[Greg Hermann]

At 11:45 AM 7/30/02, Eric Fahlgren wrote:

>Vaporization may enhance BSFC to a point but it is to the detriment of power,
>as the vaporized fuel consumes valuable space that otherwise would be taken up
>by oxygen.  The beauty of the Weber is that it _atomizes_ fuel properly, with
>lots of fuel particles 8 microns or smaller, thus allowing for high fuel
>density
>and low BSFC simultaneously, maximizing both efficiency and power.

Ahhh--the clues are beginning to mate !! Could it be a full moon today ?? :-)

Well said, Eric !
>
>I wonder if the Audi guys with their direct injection are bypassing
>atomization,
>and just vaporizing fuel in the chamber (shoot it on something hot)?  This
>would
>result in the good burn/high HP numbers and lowered BSFC, and could be
>accomplished
>if they time injection after the intake valve is closed.  At the very
>least, they
>get good shear at the huge pressures they run (something like 23kpsi at
>the rail).

Note that there are three basic quality grades of (oil) burners for
industrial boilers: Mechanical atomization (high pressure); air atomization
(compressed air), and steam atomization. (In order of increasing quality.)

Steam atomization is not particularly relevant for IC engines, but suffice
to note that steam has a significanly lower molecular weigh (18) than air
(average 29), and therefore has a much higher sonic (Mach 1) velocity than
air does, and that this has a LOT to do with why it will give better fuel
atomization.

Greg



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