Fuel Atomisation

[David Gregory]

I just want to say that i'm not taking sides, as one would say, with those
who violated the user agreement(as an aside I'm genuinely puzzled because
these people don't seem to see any harm or wrong in what they did).
However, I'm probably sticking my nose where i shouldn't... but here goes
anyway.

Aparrently, the heat of vaporiztion for Gasoline @60 degrees F is 150 Btu/lb
(ick, English units).
The heat of combustion is aproximately 18,000-19,000 Btu/lb of fuel.
(http://www.afdc.doe.gov/pdfs/fueltable.pdf)

So, the heat of vaporization represesnts less than 1.0% of the total heat
available due to combustion.  Now also, if one heats the fuel prior to its
entry to the combustion chamber, with energy from the previous combustion
event, there is no net loss of heat to the cycle (unlike cooling losses)
because the heat taken from one combustion event is added to the next.  So
in that respect, i don't see the disadvantage to "preheating" the fuel to
vaporize it.

However, I'm willing to defer on the issue of mixture cooling in the chamber
due to vaporiztion.  According to my estimates, it would seem that the
vaporization of the fuel could lower the temperature of the mixture by as
much as 23 degrees C.  Significant?  I would think so.  But my "estimate" is
very crude and I have no practical experience in this area (tho i soon will
i think).

As you (greg) are obviously an admirer of weber carbs, I'm wondering if
maybe you could put the shoe on the other foot (so to speak) and talk to the
issues of why carbs were abandoned in favor of EFI.  And I'm aware that
currently it is legislated that production cars be EFI, but i'm wondering
about motorsports applications which chose to go EFI route(i suppose NASCAR
and some drag racing would be notable exceptions).

/dones flame suit/

David

PS:  am i correct that a carb which was setup to run at high altitude would
run rich at sea level?  or do i have that backwards?

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