Two Guys Rally

Keeping Racecars Cool
[ July 22nd, 2008 ] By: Charles Smith Posted in » How To, Tips and Tricks

While racecars are usually most definitely awesome, today’s weather reminded me they are pretty effing hot inside them. In the quest to save weight (translation: saving time on your laps/stages) common things are kept off the car. Air conditioning is gone, underbody/frame insulation is gone and the lexan windows usually dont roll down. Combine that with the fact that a racecar’s engine runs quite a bit hotter and cars with antilag systems (ALS) have exhaust temperatures above 1000 ºC the car’s interior will be hotter when running. However there are a few tricks to keeping the cabin temperatures survivable:

Air Vents

Racecars have a love hate relationship with air. At really high speeds it slows them down and sometimes even makes them crash, but it also cools their engines. In a similar fashion, it can help cool the cabin and driver(s). Keeping your drivers alive means getting them nice cool air to breath. Good helmets allow the driver to breath and it lets sweat do its work at cooling the driver(s) down. NASCAR likes to use forced air helmets that push air through the helmet, while Rally tends to use open face helmets (very breathable and you can yell at your driver in them).

In order to let a helmet do its job air needs to be getting to the driver(s) from outside. Vents to the cabin are nice for this. Rally cars often have a vent on the top center of the car to let air in through a diffuser so the drivers can breath and cool off. Air also has to exit the cabin, but if your windows are closed how can it do that? Closable vents in the back windows help with getting air out of the car, however in a Rally application I would suggest a filter on them (dust likes to come into the car otherwise). Andrew Comrie-Picard’s Mitsubishi is a shining example of common air ducting.

Window Tint

Sunlight heats up the cabin majorly. Ever been burned by a seatbelt buckle that was left in sunlight on a hot day? I know I have. Tinting a racecar’s windows with reflective tint can reduce any sunlight that is causing the cabin to get real hot. While black tint works to combat cabin temperatures, mirror tint works better (more reflection, less absorption) as it will not radiate as much heat through the glass into the cabin.

Roof Paint

Another way to keep the cabin temperatures from skyrocketing due to sunlight is to paint the roof of the car. The roof of the car is often not seen by spectators, so diverting from your colorscheme is not as big a deal. Painting the roof white will keep it from absorbing as much heat from the sun and further lowering the temperatures in the cabin.

Interior Paint

The interior is exposed to light too! Roll cages and the inside of the car frame make up a large surface that can absorb even more heat. Painting them white keeps them from absorbing as much heat. Plus a consistent interior color makes the car look neater and better organized. Also white shows everything wrong(great trait in a racecar) like: all sorts of leaks including exhaust, cracks and where you dropped your notes pen.

Insulate Exhaust Pipes

Exhaust pipes in racecars get extremely hot. They get way hotter than the exhaust on a street car so there is a lot more heat that comes off of them and into the cabin. Wrapping the exhaust in heat insulation might add a couple pounds, but it might give you a better performing engine. Higher exhaust gas temperatures means higher exhaust gas velocity, and if you’re running a turbo this means a faster spooling turbo. Not only will you get a possible gain in your engine, the cabin temps will drop. A normal exhaust will radiate heat into the metal on the underside of the cabin (a good amount of it too) which will transfer into the cabin. 1000ºC exhaust gas will conduct massive amounts of heat through a thin piece of metal(exhaust piping).

Regardless of what you’re racing doing everything you can to combat high cabin temperature will make your racedays more enjoyable and more consistent. Heat fatigues people, and tired drivers are dangerous drivers. That one, came straight out of a DMV Manual.