Quote:
Originally Posted by johnlvs2run
Basjoos, what is your opinion on this? I'm planning to have the same type of nose as Aerohead & The donkey CRX. I'm thinking to cut the plastic at 7 or 8 inches from the ground, but wondering if 6 inches would be better.
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I didn't install an air dam on my car, so I can't answer your question directly. Since I installed smooth underpanelling and greatly lowered the stagnation point to divert up and over most of the air that might have gone under the car, I didn't feel I needed an air dam considering its negative benefits; increased frontal area and their unintended function as road kill possum/raccoon scoops, which often damages them when you pass over one. If you look at the ultra low Cd solar racing cars, none of them have air dams. Rather they have smooth bellies, skinny wheels and lots of ground clearance. Sort of like an aircraft fuselage flying close to the ground, and I decided to go that route with my car as much as I could. An air dam is quick and easy way to divert air away from the rough and draggy underside found on most cars. It also increases down force by creating a low pressure pocket under the car. In the typical opened bottomed engine compartment, this low pressure pocket also increases air flow through the radiator, which is a benefit in the wide open throttle world of racing, but not necessarily so when driving for mileage since extra cooling equals extra drag.
To get back to your question about airdam ground clearance, I made most of my ground effects items (wheel spats, side skirts, etc.) of coroplast, so I deliberately made them excessively low, painted them with black spray paint, then after a few days of driving, noticed where the paint had been scraped off by contact with pavement, curbs, etc., then trimmed away the paint skinned coroplast, repainted, drove some more, trimmed, repeat, until I had everything raised up to a level where they didn't rub the road very often. I keep all of the coroplast on my car that is exposed to direct sunlight painted to keep the sun's ultraviolet from deteriorating the coroplast.
The CX also didn't come with the "rubber" side trim, probably to reduce costs rather than to reduce weight. On my car I covered the indents in the sheet metal where the trim would have gone with coroplast to make the sides smooth and eliminate the small amount of turbulence that those indents would introduce along the sides of the car.