As racers, we are always looking for that little edge against our competitors. Some of those advantages come at great cost and time, like an engine rebuild or new dual-adjustable struts. Conversely, there are other modifications that don’t cost much and can be purchased at your local home-improvement store. We are talking about building your own splitter, using basic tools and skills, and about $60 in materials from Home Depot.
I don’t claim to be an aerodynamic specialist. I don’t have a wind tunnel. I certainly don’t model pieces in clay and run them through fluid dynamics tests to see if they lower the drag on my racecar. I simply walk around the paddock, see what the teams who win races are doing — then I shamelessly steal and copy their ideas. When it comes to a front splitter, the only knowledge I can provide you is this: Your racecar is a big fat brick trying to knock a massive hole in a hard wall of air. Air acts like a fluid and it has connective properties. The plan is to cut the air that is going under your car from the air that is going over and around your car, so that air loses its connectivity and stops fighting with itself at the front of your car, slowing you down. To be honest, that information may be completely inaccurate. Here is what I really know for sure: splitters just look cool.
To build one, all you need is some plywood — we used 15/32nds thickness — some plastic garden lawn edging pieces, a couple of pieces of flat steel, some rivets, and a few hours to kill. If you have some basic woodworking tools, you are all set. Just think, if your middle school shop teacher could see you now.
One of the first things to look at when designing your splitter is your rulebook. For Honda Challenge 4, the rules are specific that the splitter cannot protrude from the front of the vehicle. To ensure our splitter was legal, we used a plumb bob to outline the front shape of the car on a piece of plywood that was taped to the floor. We taped it so it would stop moving around while we worked. A simple jigsaw cut the rounded front shape and we had our basic splitter design. We decided to build a second splitter at the same time because we have learned while racing in NASA that splitters tend to die. Anything that is low to the ground and on the front of a racecar is going to have a short lifespan. For that reason we built two from the onset.
Regarding the sudden death of splitters, I’m reminded of the hardware materials we chose to use — and not to use. The simple way to connect your plastic vertical surfaces — the plastic garden edging used as fascia — is with self-tapping screws. The problem is that you are essentially building your own booby trap. Nothing goes through a race tire quicker than a self-tapping screw. So putting 40 of them in the lower leading edge of your car, directly in front of all four of your race tires is a bad idea. We used rivets to hold the vertical plastic pieces in place to avoid sabotaging ourselves.
To mount the splitter to the car, we used flat steel, which we heated and bent to a 90-degree angle. On the lower portion of the steel, we welded on some nuts to easily mount the splitter board while under the car. The upper portion of the steel we slotted to mount to the side of the radiator support. We slotted the metal so we could adjust the height of the splitter for some tuning ability. To help adjust the height of our splitter, to ensure it was level side to side and front to back, we took two 4X4s and ran them through a table saw. The 4X4s then had two different set-up heights. We would set the two pieces of wood under the splitter — at whichever splitter height we wanted — and then tighten the bolts that hold the metal plates to the car. Super easy.
Did the front splitter make the car 4 seconds a lap quicker? Nope. But it certainly didn’t make the car any slower, certainly at fast tracks like California Speedway in Fontana, Calif. We did find one quick disadvantage to our super cool looking splitter: The car no longer can make it up the trailer ramp. Yup, that means the splitter has to come off and on every time we want to get the car in the trailer. Racing sure is fun!