[Diy_efi] Evaporative fuel injection (evolution of the evap carby)

[Adam Wade]

--- Ben P <benof1987 at hotmail.com> wrote:

> First up I am assuming that your claims of huge
> detonation, pre-ignition, and (most of the) lack
> of power centre around intake temperatures.

That's part of it.  Smokey Yunick was using a
draw-through turbocharger, and intake temps were
supposedly above 100 C; in addition, you're running a
very lean mixture, which will contribute toward
detonation; the extremely high intake temp plus forced
induction would account for the pre-ignition

> As for the fuel condensing on the walls of the
> intake manifold, this should not be a problem with
> my idea.

With Yunick's setup, likely not.  If, as you
suggested, the intake temp does not rise much,
"stealing" the heat from the vaporized fuel, that
would cool the vaporized fuel a lot (assuming again no
blower), and I would be concerned that the less
volatile fractions might condense, especially if the
manifold walls are below the temp of the intake air. 
I think this one would bear experimental observation;
it might happen, or it might not (for any given fuel;
I was assuming pump gas).

> I am wearing the second low power argument for now
> (fuels displacing intake air), but even at a 12:1
> AFR, the fuel would only take just over 7.5% of the
> volume, for the same 7.5% power loss (plus the
> losses due to heat though, so maybe 10-12% overall).

Except in port injection engines, much of the fuel
remains in liquid form until after it is inside the
combustion chamber, so the difference between your
example and a "normal" fueling setup would be larger. 
Yunick used turbocharging to make up for the lost air
mass and to keep the fuel in vapor form (and it should
be noted that most experts in the field concluded that
Yunick had some additional trickery, probably in fuel
additives, that allowed this to work.  GM licensed the
technology from him, but never put it into
production...  That speaks volumes in my mind).

> And what on earth do you mean by "an inability to
> fuel appropriately for large values of delta alpha",
> I can't understand it.

Whack the throttle open fast, and see if the fueling
can be richened enough, quickly enough, to keep the
vehicle from stumbling.  Since it seems there is a
time factor here, as well as very lean running, I
doubt very much that throttle response could be
maintained, definitely without ruining the desired
fuel economy.

> *I checked out the Smokey Yunick thing and couldnt
> make sense of any information. I get its claims, but
> no data on its workings.

Apparently he was tight-lipped on such details, and
nothing was ever done with it after the initial splash
of publicity.  Something more was going on there than
what meets the eye, methinks...

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