There are two types of cars built for racing. One type is built for the short track where the speeds are lower and the turns are tighter. The other type is for the super speedways where the speeds are faster and the turns are wider. The Bristol Motor Speedway located in Tennessee and a super speedway would be like the one in Daytona, Florida. When making a short track car the aspect of down force is concentrated on because down force helps the car grip the track better since it is made lower to the ground than others. Also the body of the car is placed further back on the frame of the car and the front fenders and are more curved. With a great amount of down force the car will be better able to handle the turns of the track as quickly as possible. Since the brakes and engine conducts more heat, the cars are made with more grill vents where air goes directly to the brakes.
The cars on the super speedway need to keep high speeds at all times, even when going into the turns. The banking on the track is high for this purpose and the body of the cars is placed more to the front of the frame to reduce drag. Reducing drag is important because if they do not the cars will not be able to go fast enough. Since the cars travel at higher speeds there are not as many air vents to cool the engines and brakes, as it is not necessary.
Checking the requirements from the SCCA or the speedway officials is the most important thing that you can do to make an acceptable speedway car. You should pay close attention to what they expect on the inside and outside of the car. You also need to know exactly how fast and how far the car will be traveling so that you know how much horsepower the car needs to have to perform properly, how munch ventilation is needed for the engine and brakes so that injuries are avoided and what fluids would be best for the car to make sure that is as optimum racing ability. Sometimes just the way the car curved can increase the ability for the car to catch the wind and increase speed, but it can be more dangerous if done the wrong way.
You must be careful and, like everything else in life, do the research of have an expert do it for you. Having poor bearings on the wheel hubs can be a recipe for disaster. Make sure that every single bolt is tightened. Check and recheck. You can never be too careful. Make sure the fuel pump and all other related parts are in perfect working order. Just to be safe, you could brand new ones on before each and every race to insure your safety and the safety of others on the speedway with you. You may be able to use a car instead of a motorcycle on a dirt track, but checking with the appropriate officials is always the best way to go. Different parts ay be necessary to use.