Todd Carrico wrote:

I have been thinking quite a bit about this, and this
is what I have come up with.

I think we all agree that the stock metering system must
go.

I think that we all agree that pre-mix is pretty damn hard
to beat.

however, this is the argument that I have been going
over and over.  I will spell it out for the record.

Maybe a thousand years from know someone will dig this
up and say that our society was not as evolved as it was
once thought to be...

The argument:

For acurate engine tuning, I think that air/fuel ratio
should be as stable as possible.

With that said,

By pre-mixing, the ratio of oil to fuel will vary, if ever so
slightly.  I don't imagine the fuel boy will always put
in nice round numbers of gallons.  And I don't think
that I would be able to always put in nice round
numbers of oz's either.  After all we humans tend to
introduce the biggest number of errors.

It would take some testing to see how far out
you could get the ratio before you needed to re-tune, but
perhaps we already know that....

By mixing the fuel and oil with a metering device, you would
have better control of the mixture, however, a fuel injected
engine returns the unused fuel (fuel/oil) to the tank.  This would
effectivly continue to increase the ratio of the oil to fuel, and would
be undesirable.

Very good point indeed.

You could get arround this by metering fuel/oil into a sump,
and then return the overflow to the sump.  This would keep
the ratio constant, but would probably require more parts to
fail.

Having a seperate oil tank that you could meter oil into the
fuel tank on demand, would seem to be the best of both worlds.
The trick would be to get just the correct amount of oil for the
amount of fuel that was added.  This would be tricky, but I am
confident that it can be worked out.  All we need to know is what
is the range that we are looking for.  1 oz per gallon is very easy
to work with, but if we are working with volume, as in a manual pump,
this will have to be calibrated.  We need an acurate range with
which we can say that engine tuning, and apex seal cooling, are
reasonably un-affected.  This will let us know how close we need
to be with our hand metering.

As for getting the fuel and oil mixed,
By the time the fuel has gotten to the fuel injectors, it would have
to go through the fuel tank bafles, the tank screens, the sump, the
fuel filter, and a fuel pump.  It should be well mixed, even without the
wing waggle.  With a sump large enough, you could
be assured that by the time you got into the air, you would just be
getting to your "new" mix.  With the seperate oil tank, you would have
a convienient storage place for our precious fluid, and not have
to rely on carying crates of the stuff in our not so large bagage
areas.

Sorry for the length, but I thought this should get into the Archives.

tc

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