Cool, fast air

[Scott Fisher <sefisher@domain.elided>]

While I've been enjoying my new-to-me '74 Spider, I've been thinking of
things I want to do to it to make it more, well, mine.  One of those
will probably happen before the summer is much older: the removal of the
engine-driven cooling fan, to be replaced by a fused, thermostatic
electric fan, much like the one I installed in the '67 GT 1300 Junior.  

I'm expecting three primary benefits from this.  First is quicker
warm-up in the mornings; I'm often still in the cool zone (below 180 F)
when I get on the freeway, and while there's probably nothing wrong with
that, I still think about all the different shapes, sizes and kinds of
metal in the engine and go easy with the right foot.  Gotta get ahead of
those SUVs, you know.

Second is better cooling in hot weather.  I definitely experienced this
with the electric fan I installed in my '67, and here I think is why. 
An engine-driven fan runs at high speed when the car is moving quickly,
and at low speed when the car is standing still.  It should be obvious
that this is just the opposite of what you want, especially here in
California in the summer: you want lots of airflow from the fan when the
car is standing still, but require little or no airflow from the fan
when the car is moving.  The electric fan ramps up to full speed almost
instantly, so when I'm stuck in traffic on the way home in 92-degree
weather, the fan will still push as much air through the radiator as
though I was traveling at 60 mph.

And third, of course, is the reduction in parasitic losses caused by the
engine-driven fan.  I've heard figures as high as 6 or 7 bhp quoted as
the power consumed by the engine fan at 6000 RPM, and I see that on the
tach as many times a day as I can.  Either way, the adoption of electric
fans has been almost universal now by car companies looking to maximize
their fuel economy, and the only difference between fuel economy and
high performance is whether you're optimizing for distance or time for a
given amount of fuel consumed.

Electrically, I'm planning to install it exactly as I did on my Junior,
or maybe even a simpler way that just occured to me: wire +12v to the
battery + lead, -12v to the battery - lead.  Then install two items in
the wiring: an inline fuse of the recommended amperage (I *think* it's
25A but I'm not sure), and a thermostatic switch.  To recap what I
learned when I installed the first fan unit, the position of the
thermostat sensor determines how soon your fan comes on: higher up in
the radiator means it starts sooner (because the hot water gets there
faster and hasn't had a chance to cool yet), lower means later.  On the
'67, the sensor is about three inches down from the header tank, and the
car runs perfectly in California summer weather.

But there's something else that I'm still struggling with.  In my AR
Ricambi catalog, there are a number of different high-performance
devices, ranging from full-race cams meant to be used with
high-compression pistons, fully ported heads, and racing-type extractor
exhaust systems, down to the Bosch cone-style air filter that started
the thread some time ago.

One of the devices that intrigues me is the Shankle Quadraflow.  It's
essentially four steel tubes, 4-1/2" long, grouped as two pair, with air
filters on one end of each pair.  The other ends of the tubes are
designed to slip into the Spica intake, where the stock Alfa airbox
slips in now; the stock Alfa airbox can then be set aside temporarily.

So while I seriously doubt that the air filters alone could make any
significant difference in the car's performance, I'm less sure about the
ram effect of the 4-1/2" long tubes.  Having just posted the theory
behind ram tubes, I'm familiar with the basic concept.  ARR's catalog
claims that the 4-1/2" length was determined by testing to be the
optimum for RPM ranges on the street (as opposed to full-on track use);
they further claim as much as a 7-bhp increase after installing these
ram tubes.  And I don't know enough engineering to be able to say that
4-1/2" times 40mm will work at X RPM but not at Y.  Surely someone here
does...

The good news appears to be that this Quadraflow unit seems to be
simplicity itself to install, and is completely reversible.  I would be
able to return to the stock unit in a matter of minutes, should that
become necessary.  It looks like something I could install in the
paddock for track events and autocrosses, then reinstall the stock unit
for the drive home.  So from a standpoint of fuss, bother, and easy
reversibility of changes, the Quadraflow seems to be a good thing.

It's just that question of how well it works.

Has anybody used these?  Better still, has anybody performed
before-and-after tests with these, or tested them on a flow bench with
the stock Spica unit to see whether they improve flow, and at what flow
rate?  Best of all, is there anybody in the Bay Area who has a set,
would be willing to let me install them on my car, make some tests, and
then either sell them to me or let me buy my own?

Barring that... anybody know what the going rate for these things is
today?   (I have an old catalog that requires a separate price list,
which I haven't got.)  If they're reasonably priced, I may just buy them
and try them out.  

Now... for the cool-air-intake part of the discussion.  If these work,
the next step would be to build a heat shield under them, designed to
keep heat from the engine away from the intake tubes, then to duct in
cool air from one of two places: either in front of the radiator shroud
(as Alfa have already done), or from the rear of the bonnet.  Both of
those are high-pressure areas well outside the hot zone underhood; it
may or may not be necessary to build a pressurized airbox with the ends
of the velocity stacks inside it (though Alfa certainly thought it
was...)  And of course, if I had a Spider with a ratty nose cone, I
might think about Ferrari 250 GTO-style half-moon air ducts, one of
which would line up with the air intake.  Yeah, that'd be very trick.
:-)

And for a final question -- considering only the lengths of the runners
from the outer end of the Spica manifold to where they terminate inside
the stock airbox, *how long are they*?

I think I'm going to do some peering under my hood with a tape measure
before I call Ricambi with my MasterCard number...  I'll let you know.

- --Scott Fisher
  '74 Spider
  '67 GT 1300 Junior

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End of alfa-digest V7 #868
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