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Auto airflow.

  1. Feb 18, 2008 #1
    I am hoping for some advice on airflow...in particular, guaranteeing airflow to a rear mounted radiator, in my 2.5 Triumph Spitfire.
    I have read, about low pressure, and high pressure areas, although im a little confused as to the area underneath the car.
    I understand that the lower a car is to the ground, the more the car "sucks" itself down....Bernoulli affect?
    The Triumph Spitfire has a low pressure area at rear, which , can pass exhaust gases,back into the car.
    I have heavily modified my car bodywork, in as much as i have nearly fabricated a new roof,(Am currently at "plug" stage). This roof has three vents, which will guide air to a rear mounted radiator.In addition, i flowed the roof back, similar to fastback design, which in that case allowed the car to gain 7mph top end speed.
    Now im looking to enhance the overall flow, to rear radiator, by using the under car air.
    The rear radiator will be mounted in the boot area, and angled, with two cooling fans.
    I was thinking, that i could use a panel, gathering air from beneath the car, and directing it at radiator.
    I have some photos on my blog, if these will help,
    Any advice, comments, or observations greatly appreciated.
  2. jcsd
  3. Feb 18, 2008 #2


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    It is tough to generalize that just because a car is closer to the ground the pressure will be lower. Perhaps it is. I would think its a function of body style and geometry, not location. Anyways, lets say it is. What about using some kind of scoop system much like engines use? Of course you would have to make sure that your radiator could handle the engine heat load at a standstill all by itself.
  4. Feb 18, 2008 #3
    Hi FredGarvin, thank you for your reply.
    The three vents i have already, directing air to rear rad', could be classed as scoops, i think, (????), but i still feel i have to at least double the guaranteed air to rear radiator.
    Do you mean scoops below boot area drawing air passing underneath car?
    I have to be careful, in that aesthetically i dont want the car to look like it came from the "Mad Max" design school. So adding more scoops above, or on outer bodywork is a no no.Hence idea of drawing air from below car.
    The rear boot section will be completely open, IE, no boot lid. And will have twin cooling fans. In my previous experience of using this car, (Although now with more HP), i feel this will be enough for standstill.

    Incidentally, how can i calculate downforce pressure, for a given area, and angled wing please?
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