[DeTomaso] Ghetto Engineering Part 1

Mad Dog Antenucci teampantera at yahoo.com
Fri Oct 17 18:05:43 EDT 2008


Good stuff Rookie!

Scott Couchman <scottcouchman at yahoo.com> wrote:  





I decided to try and build on some of the aero work Goran
has been doing. I bought20’ of 5/16” flexible clear vinyl tubing for $4 from
Home Depot and fashioned aU-shaped manometer at one end and filled it with
water. I then used the other end tomap the pressure at different locations on
the surface of my ’72 Pantera while I droveat near highway speeds.



With the manometer end of the tubing duct taped to the dash, and the other end
leadingout the window and duct taped outside at the base of the windshield, I
headed south onI5 while monitoring the change in the meniscus level in the
manometer. I decided to trydifferent speeds and measure the pressure at
different locations along the centerline ofthe car. I started at the base of
the windshield because I understand that this is ahigh-pressure region. The
change in the meniscus level confirmed that. There wasn’tmuch change at low
speed, but the movement was very noticeable as I accelerated intothe flow of
traffic. I decided that I should repeat the test this time headed north and notsurprisingly got similar results. As I hit 90 in the ‘slow lane’, I passed a
CaliforniaHighway patrol officer giving a greeting to a Chrysler Pacifica
driver on the side of thefreeway. I decided to take the next exit and stopped
in the back parking lot of a HomeDepot to wait out the officer and to move the
end of the tubing to the top of thewindshield.

 

I repeated this test a couple of time, trying to be as
discrete as possible to avoidattention. Note- it’s difficult to be discrete
going 90mph in a yellow Pantera in themiddle of the day on the busy 5fwy!
There was a C6 that was shadowing me and Icouldn’t tell if he was trying to
figure out what I was driving or what I was doing withthis tubing hanging out
the window. As I passed the Highway Patrol, the red light cameon

fortunately,
it was the red light on my gas gauge (at least now I know it stillworks!), so
I ducked into a gas station before the carburetor agreed with the warninglight
that the tank was empty.

 

DATA – At the based of the windshield, the meniscus moved
down .5” at 80mph and1” at 90mph. Remember, to convert to pressure, the column
of water is twice that, or1” at 80 and 2” at 90. This was consistent with what
I expected. At the top of thewindshield, the meniscus moved UP 1” at 80 and 2”
at 90! This really surprised me.That’s 2” and 4” of water, or a total of 3”
and 5” difference between the base and thetop of the windshield! I measured
the pressure at the rear of the roof, but the realreason I was doing this test
was to try to find a high pressure location to mount an oilcooler to keep my
oil below 275F during open road racing.

 

CONCLUSIONS – First, a manometer made out of flexible clear
plastic vinyl tubing isa reasonable approach to measure airflow around a
Pantera at near highway speed.Second, if you’re planning to feed your engine
with cool air from the top of thewindshield, I hope you have different data
than I found. Third, I need to measure airtemperature at the same locations
because pressure is only part of the equation. Fourth,I need to do more
pressure mapping, but I think I’ve found a location to mounting an oilcooler.
Fifth, extrapolating from 90mph to 150mph isn’t practical so I need to do moretesting at higher speeds.

 

By the time I finished 4 sets of tests, the freeway was
starting to slow with afternoon
commuters, so I decided to head back to the
garage and find the last bottle of
MillerLite in the ‘frig and settle in for an
afternoon nap. I have more work to do, but
I’ve already found some interesting
results. But before I do more testing, I need to pull
the distributor so I can
get it re-curved this weekend. I’ve got some photos of the test if
anyone is
interested. OBTW, if you’re interested in knowing where to mount the oil
cooler, show up at the May Open Road Race in Ely and I’ll show you!



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Mad Dawg Antenucci 
Team Pantera Racing 
  The 1st & still the only vintage race team in open road racing 
www.teampanteraracing.com



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