Story by Budd Stanley
Last month we discussed the aerodynamic impacts of a rear diffuser on the back of a car. This month, let’s talk front splitters. If you are going to go to the trouble of building a flat under-pan (if your car doesn’t already come with one), you’re not going to want to forget the a front splitter. Unlike the rear diffuser, which doesn’t really work unless your car is sitting on the ground and has a proper flat-bottom, a front splitter is much more effective in everyday circumstances.
First, what is a front splitter and what does it do? Quite simply, a front splitter is a lip that sticks out from under the front bumper into the flow of air impacting the front of the car. Its purpose is just as its name implies, it splits the air coming towards the car. Splitting the air has two important effects on a car’s handling. One, it reduces the amount of air and therefore the air pressure going under the car. This low pressure air is directed along the flat bottom and on to the rear diffuser, setting the diffuser up to do its job in the rear.
Second, air that is directed over top of the splitter hits the bumper, or air dam. Here, the air gets curled into a back eddy, producing a high-pressure area. And with any surface having low-pressure underneath and high pressure on top, you’ve got yourself down force.
All seems simple and easy, right? So now you’re thinking of making one for your own car, right? Well, like a diffuser, a splitter is only useful in a low-riding car, but it is much more useful when you do have a low car and easier to construct. Also you will need a bumper with a flat bottom to give a good tight fit between the splitter and the air dam. Any large holes will reduce the effectiveness of the splitter.
You are going to want to use a strong material such as carbon fibre, of if you didn’t win the lottery, aluminum or polycarbonate plastic. Second, you’ll need to fasten the splitter to both a subframe and the front bumper securely to handle the down force it will create. If you can’t stand on the splitter without breaking it under your weight, you aren’t doing it right. Other than that, it’s pretty simple – build a platform around the shape of your lower bumper, leaving a 2-to-4 inch lip on the end to reach out into the airflow. The splitter should be the full width of the bumper and should reach as far back under the engine as possible, as this will create the best results as well as offering several good mounting surfaces. Finally make sure that the splitter is mountedparallel to the ground. The flatter it is to the surface the better it will work.