Aerodynamics is probably the most important aspect of the modern race car. Those of us who are F1 fans see how those teams spend untold sums of money, expend more man hours in wind tunnels and employ unimaginable computer power to gain just the slightest advantage in down force or drag reduction. Who would have imagined a couple of years ago that the engines exhaust gases could be used to increase downforce? Or that how that was executed would be the difference between a world beater and a mid pack car.
But how, if at all, does aerodynamics effect our world, where the bodywork is made from carbon fiber or fiberglass, and all made from the same molds? The answer isn’t simple, and I will freely admit that I dont know everything that is going on here.
But we do know that in the days when steel roofs were required, things were creative. A steel roof was required to prevent the cheating up of the windshield. However a stock roof will not fit the molded bodywork. Not only was the metal stretched, but it was sectioned. In other words a pie shaped section cut out so that the stock windshield fits but the greenhouse is as small as possible.
But you say that’s just vintage cars whats that got to do with the cars we run now? True, point well taken. But remember that the laws of physics are the same for an F1 car or a GT1 car. And its all about managing the flow of air around the vehicle and underneath the car. So I will just point some things in no particular order. And remember, in making these points I am not accusing anybody of doing anything.
First, back in the old days of the Trans-Am series they required that the body not below the line of the chassis. As part of the tech inspection a straight edge be placed across the bottom of the car. The advantage of course being that dropping the body below the frame, (which has a belly pan) you create diffuser tunnels between the door and the frame rail.
Even if the body is even with the frame rails, you can do the same thing with the filler panels between the body and frame. This requires a little creativity so as not to be conspicuous.
Speaking of the area between the door panel and the car itself, I have seen some radiused pieces placed at the front of the filler panel. The purpose was obvious, but how do you get that air out from under the car? Its blocked by the rear wheel tub, so wouldnt it be better to get it out at the front wheel opening?
A few years ago one of the major Ford teams cars cars appeared to be a little different. Just by observation it seemed that the rear undertray had more of a slope than the other Fords. Of course the part had the proper approval stickers.
The mesh on the grill opening can effect the amount of downforce on the front of the car. Of course the finer the mesh the less air can get through. And using one consistent mesh is just a matter of convenience right?
Speaking of Fords, the 93-up Mustang had a huge flat rear deck. That made these cars more responsive to body rake. By getting that deck exposed to more airflow, you increased the downforce. Almost like using a larger spoiler. Other makes may have the same issues.
Dive planes of course are useful in tuning the front end.
And the primary goal is doing anything possible to first prevent air from getting under the car, secondly to exhaust the air that does get under the front of the car. I had a steel bodied Mustang, that used a steel hood, with a scoop, that had all the reinforcement removed. Down the straightaway the rear of the hood would rise up to the full extent of the hood pins. Perhaps 6″ in the center. If we could have prevented that it could have meant some nice gains. Food for thought.
If its allowed by the rules, opening up where the rear license plate was allows a place to exhaust air from the rear. many people use this as a place to place an oil cooler for the trans or rear.
And of course the wickerbill on the rear end can be used as a tuning tool, as well as the angle of the wing itself will increase rear downforce.
Like anything else when you change one end of the car it effects the other as well. We’ve just thrown a few things out there, and obviously just scratched the surface of what may be going on. But if you look closely there may be things that make you say “hmmm?”