Lift/downforce physics info??

[blue2000s]

Expanding a bit on Insite's explaination, the car is part of the lift. The air flow pattern is influenced by the shape of the body work. The lift created by an airfoil is heavily influenced by that flow. If you look at the airfoil on the boxster, it's basicaly just a nearly vertical wall which would have almost no lift if it weren't attached to a car.

There are countless tables of airfoil lift and drag coefficients developed for the aviation industry, relating to Reynolds number typically, but I'd be very surprised if you ever found coeficients that you could plug into the simplified form of the navier-stokes equation you've got there relating to a specific car.

[insite]

all true. also, it might help to explain the difference between a wing and a spoiler. a wing is used to actually create downforce. a spoiler is used to reduce the lift generated by the shape of the car itself.

if you think about the car in simplified form, the bottom is flat and the top is curved. air must follow a longer path to get over the car than to go under it. this means that air flowing over the car must move faster than the air flowing beneath it; the bernoulli effect causes the low pressure area above the car responsible for the lift. to reduce this lift, we can EITHER reduce the speed of the air moving over the car, or increase the speed of the air moving beneath it. a spoiler does the former. venturi tunnels under downforce cars do the latter.

in effect, the spoiler on our car is used to simply interrupt the flow of air moving over the car to slow it down relative to the air moving under the car. once this happens, the pressures above and beneath are closer and lift is reduced.

[pinzgo]

Shift Light

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Somebody can tell me where I find place to plug wire to get RPM pulse for my just added tachometer and shift light. Boxster S 2000.
Thanks for help
Jacques

[Topless]

There used to be some 986 wind tunnel data floating around on the internet. It had pretty good data on the effects of the OEM spoiler. I checked my tech bookmarks but could not find it. Google is your friend. If you find the site you will also get lift/drag data for many cars, spoilers and wings. Good luck. Hope it helps.