[DeTomaso] New Rear Window and Engine-Bay Cooling Fan

Asa Jay Laughton asajay at asajay.com
Sun Oct 2 01:34:37 EDT 2016


Here is a direct link to the finished product:
http://www.snclocks.com/TheRestofourWorld/Autos/Technical-Bits/i-HprC5cq/A

In comparison, yes, the clay mock-up appeared to have vents in the 
decklid.  Perhaps that was something that didn't make it to the final 
design but should have in order to install rear glass; which in the 
above linked photo looks pretty awesome.
Asa

Asa Jay Laughton - W7TSC, MSgt, USAFR, Retired
&  Shelley Marie
Spokane, WA
******************************
http://w7tsc.org
http://www.teampanteraracing.com


On 10/1/2016 10:26 PM, L GRAY wrote:
> Hey guys........the car you're looking at is a clay mockup so there actually may not be a "rear window" just blank black space.
>      Also notice the vents on the rear deck lid inner sail panels to exhaust engine bay air. . . . . .
>       I'm thinking that even with a glass they still had to move all that hot air out the deck lid vents......just my thoughts.
>
> Leslie A. Gray
>
>> On Oct 1, 2016, at 10:20 PM, Asa Jay Laughton<asajay at asajay.com>  wrote:
>>    I would like to see more photos, outdoors sitting alongside other
>>    Pantera's.
>>    But with that said and only seeing the two photos you have in your
>>    gallery, my opinion has changed.  I had my doubts that it would look
>>    significantly different, but I must say that I think adding the rear
>>    window easily adds a few thousand dollars to the car's appeal.
>>    Honestly, I think it gives it a really nice clean look.  It -does- look
>>    like it's meant to be there.
>>    You did a great job of engineering to make it work.  I'm anxious to
>>    read the article.
>>    :)
>>    Asa  Jay
>> Asa Jay Laughton - W7TSC, MSgt, USAFR, Retired
>> &  Shelley Marie
>> Spokane, WA
>> ******************************
>> [1]http://w7tsc.org
>> [2]http://www.teampanteraracing.com
>>
>>    On 10/1/2016 8:11 PM, Stephen wrote:
>>
>>    For some time I have been thinking about installing a window in the
>>    opening behind 5332's engine compartment.  Originally there was meant
>>    to be glass in the opening, but, according to Tom Tjaarda, there were
>>    overheating issues and the window glass was left out.
>>
>>
>>    I decided to firstly see what would happen with the opening blocked off
>>    and the car idling.  One 70 degree F day I blocked the opening and let
>>    the car idle while I monitored the inlet air temperature via the remote
>>    for my MSD fuel injection.  With a hot engine and a 70 degree ambient
>>    air temperature I saw the inlet air temperature go up at a rate of
>>    roughly a degree Fahrenheit every 2 seconds.  I quit the experiment
>>    when the inlet air temperature hit 150F.  As an aside, I had previously
>>    noted when I was stuck in traffic on a hot day that the FI would get
>>    finicky if I sat long enough.  I figured the issue was excess
>>    temperatures even with the opening behind the engine open.
>>
>>
>>    Clearly it will get right hot in the engine compartment if one blocks
>>    off the opening.
>>
>>
>>    Earlier this year I did a series of tests to see how significant the
>>    air flow was through the opening at speed.  My testing showed the air
>>    flow through the opening was around 20 to 25 feet per second (14 to 17
>>    mph) at a road-speeds of 60 to 80 mph.  The flow through the opening
>>    equates to an air volume of around 2000 cfm at 70 mph.  If I installed
>>    glass in the opening I figured I needed to install a fan to provide a
>>    reasonable flow to keep the engine compartment from overheating -
>>    somewhere around the air flow rate when the car is going 30 mph -
>>    around 800 CFM.
>>
>>
>>    So, given I intended to install a window in the opening to keep from
>>    pulling water and dirt and rocks and grass and whatever is on the road
>>    up onto the engine when driving at speed, as well as to keep folks from
>>    being able to reach in and take whatever they wanted off the top of the
>>    engine, I figured the first step was to figure out how to keep the
>>    engine compartment cool.
>>
>>
>>    Looking at SPAL radiator fans - wow - even a 10" low profile fan puts
>>    out 800 cfm.  I thought this would be sufficient.
>>
>>
>>    Next I looked below the car to see where I could hide a fan.  Turns out
>>    there is a great space below the coolant surge and swirl tanks - just
>>    behind the bulkhead and above the frame rails.  Measurements suggested
>>    that a 10" fan would fit.
>>
>>
>>    Next - how to keep dirt and rocks and leaves and the like from getting
>>    thrown up into the fan.  I did an online search for 12 inch circular
>>    screens and found a rather novel solution - 12" stainless steel flour
>>    sieves.  Talk about a slick fit - check out this picture:
>>    [1][3]http://www.snclocks.com/TheRestofourWorld/Autos/Technical-Bits/i-mN7
>>    wzjK . You can see two of the angle brackets I used to mount the
>>    fan/shroud to the frame rail and inner sill.  There is one additional
>>    bracket that mounts to the frame rail.  When mounted, as shown in the
>>    next 3 pictures in the above gallery, it is very solid and out of the
>>    way.
>>
>>
>>    I set up a SPAL PWM (pulse width modulated) fan controller with a
>>    Derale 16760 Push-in Radiator Probe to control the fan speed.  I like
>>    the PWM controllers - they ramp up fan speed as the temperature goes
>>    above the temperature you choose as your lower target.  Then, if the
>>    temperature continues to go up, the fan is at its maximum speed when
>>    the temperature hits your upper target.  If you have a second fan, it
>>    will turn on when the temperature hits your upper target.  I use one of
>>    these on the radiator fans for 5332 and on the fans for our '69 XKE.
>>
>>
>>    I mounted the temperature sensor to the fuel line going to the FI
>>    throttle body and set the controller to start spinning the fan at 140F,
>>    with an upper limit of 150F, whereupon the fan is spinning at full
>>    speed.
>>
>>
>>    With the opening blocked, the fan, at full speed, brings the inlet air
>>    temperature to the FI system down at about 2 degrees per second.
>>    Worked like a charm!
>>
>>
>>    After installing the new rear window Kels and I joined the PNW Pantera
>>    Group for a run up into British Columbia - going to a car show in
>>    Nelson.  Logged around 1200 miles on that trip:  The fan only came on
>>    once - when we restarted the car after letting it sit for 30 minutes
>>    while we were in a store.  Fan came on, temperature dropped and it shut
>>    off within 30 seconds.
>>
>>
>>    When driving at speeds over 10 mph with the rear window in place the
>>    inlet air temperature held around 40 degrees F above ambient.  This
>>    jives with what James Fusco told me - he explained that "the air that
>>    comes into the engine compartment has already gone through the radiator
>>    and along the bottom of the car".  OK - that makes sense.  And, it is
>>    apparent that, even at fairly low speeds, there is a lot of turbulence
>>    in the engine compartment, which keeps the compartments temperatures as
>>    cool as could be expected, given that the air is coming from below the
>>    car/the radiator.
>>
>>
>>    Fortunately I mounted the engine-compartment cooling fan to one side of
>>    the engine compartment - turning it on at speed does cool the inlet air
>>    temperature.  And, when sitting still, the fan is very effective since
>>    it is likely drawing air that has not been through the radiator.
>>
>>
>>    The fan blows air up the passenger side of the engine, across the top
>>    of the engine compartment, and down the other side.
>>
>>
>>    I've included a couple of pictures of the installed window in the above
>>    referenced photo gallery, along with some pictures that I will discuss
>>    when I put together an article for the newsletter.   There are
>>    definitely some challenges to getting the rubber around the window laid
>>    in nicely - I will cover those in the article.
>>
>>
>>    I think the rear window finishes the look of the car - it is surprising
>>    to me how much more complete it makes the back of the car look.  And,
>>    before anyone howls about modifying the car - well, hmmm - it was
>>    originally intended to be there - except there was no provision for
>>    letting the engine compartment vent hot air when sitting still.
>>
>>
>>    Stephen Nelson
>>
>> References
>>
>>    1. [4]http://www.snclocks.com/TheRestofourWorld/Autos/Technical-Bits/i-mN7wzj
>> K
>>
>>
>>
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>> References
>>
>>    1. http://w7tsc.org/
>>    2. http://www.teampanteraracing.com/
>>    3. http://www.snclocks.com/TheRestofourWorld/Autos/Technical-Bits/i-mN7
>>    4. http://www.snclocks.com/TheRestofourWorld/Autos/Technical-Bits/i-mN7wzjK
>>    5. mailto:DeTomaso at server.detomasolist.com
>>    6. http://server.detomasolist.com/mailman/listinfo/detomaso
>>    7. http://www.avg.com/
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