To reach the outer threshold of usefulness. Often used to describe people who have reached a level of stress that leaves them in a semi-vegetative, shell-shocked state. Tech support folks inevitably end up like this.

Burn outs are kind of like peeling out but are always deliberate and you don't move any where. You burn out by popping the clutch and holding in the brake. The force exerted on the wheels is greater then the force exerted by the brakes and wheels start moving, the brakes on the front wheels will prevent the car or truck from moving. At this point if enough gas was given and assuming the vehicle has enough power the wheels will start spinning leaving black rubber marks on the road and smoke in the air. At some point you should let off the brake and accelerate out of there. This is also known laying down some rubber, lighting up the tires, and leaving a blackie.

As a punk teenager I think it's pretty cool. Seems to piss off cops and parents for some reason. Admittly it's pretty rough on the vehicle in question.

Drag racing is not about top speed. It is in how quickly your car can transit the 1/4 or 1/8 mile that makes up the strip, measured in elapsed time. Pure speed helps, but what really makes the difference is the initial acceleration of a car. After all if you get to speed in a hurry you carry that speed the whole time. A top fuel dragster accelerates from zero to 320 MPH in around 4.5 seconds. Zero to sixty is accomplished in around two tenths of a second. In drag racing a great start is almost everything.

This means the primary goal is traction, and that can be a real problem for cars that produce LOTS of horsepower. The more grip your drive wheels can attain, the faster you can launch. In tire terms, grip is a function of the tire compound, flex in tire itself, which is partly a function of air pressure, the size of the contact patch, the car's suspension design, ground pressure and a few other less important variables. During the 1960's specialized racing slicks were developed specifically for drag racing. They offered a wider tire, with a bigger contact patch, softer, stickier rubbers. On a stock automobile such as a Hemi road runner, a set of slicks can be worth a full second or more. By the mid sixties these special purpose 'slicks' came to dominate drag racing.

Around 1970 someone discovered that if you heated up a tire, the rubber grew even softer, providing more grip, and thus a faster launch. Burn outs came about as an attempt of pro funny car and top fuel racers to heat their tires before making a run. A mix of water and chlorine bleach was poured on the race track in front of the tires. The driver would rev up the motor, and drop the clutch. The drive wheels would spin initially, and then catch launching the car down the track. A normal byproduct was a thick cloud of white smoke, that billowed out from behind the cars. Then they would back up, stage and race.

Cars looked really cool doing their burn out. Each left a wake of thick smoke as the darted down the track. Burn outs helped build up anticipation for the upcoming race. Finally, each burnout was accompanied with the roar of a race motor, itself a pretty exhilerating thing. Really nasty racing V-8s produce a gutteral, low shriek that is enough to frighten Godzilla on a bad hair day. Burn outs proved really popular with spectators. And with amateur racers as well. Many had built thumpin' engines easily capable of overpowering their tires, and they wanted those extra tenths as well. Plus amateurs liked the attention. Any teenager can tell you that breaking your tires loose is the sign of a powerful car. Or at least one that needs more tire. Anybody who builds a hot rod will be asked to spin their tires. It's just part of human nature to want that. And it's human nature to want to be the center of attention. Racers quickly discovered that burn outs drew stares.

Race promoters aren't dumb. If burnouts were popular both with fans and at least the less serious racers, promoters decided to give the people what they want, more burn outs. Which led to burn out contests.

To prepare your car for a burn out contest, it helps to have a race prepared V-8 under the hood so you have enough reserve power to overpower your tires. There is no limit to the amount of money you can spend obtaining a wild ass engine. But a race motor isn't necessary. I've seen diesels and slant sixes competing in a burnout contest. Any bone stock sixties muscle car can melt its tires in a heartbeat. Remember the idea is to overpower your tires, and under the right circumstances most engines will. Take off those wide, soft slicks and replace them with skinny little tires. Skinny little tires produce less traction and they're cheaper, which makes them easier to replace once you've ground them off going nowhere. Nor do you need cool mags, steel wheels will do. Remember, you aren't planning to move during a burn out contest, so you really won't need grip.

Second, install a brake proportioning valve in your brake lines right after the master cylinder and turn off your rear brakes. As an alternative, you can adjust your rear brakes very far out (distant from the rotor or drums). That will make you rear brakes slow to grab. The valve will cost you about $100, and considerable labor dialing the correct proportion back in when you head back to the street. But it allows you to hold the car in place with the front brakes, while you melt down your rear tires. Or perhaps burn through them through, as I saw one Dodge Dart do while competing at the Mopar nationals. The dart had completely disappeared in its own tire smoke when a loud bang announced the blown tire.

When you get to the burn out position. have someone spread water or water and bleach under your drive wheels. Brake on the undriven wheels, and floor it. You will spin in place and your tires will turn to smoke. People will cheer. You will be popular. The first ten seconds of your fifteen minutes of fame will be yours.

Why Bleach?

Stupot asked me why the bleach and water solution. I didn't know. In fact, I hadn't even thought of that seemingly obvious question. So I asked a chemist friend of mine, who calls himself Mott the Hoople online, and this is his reply.

Bleach (aka chlorox) chemical name is sodium hypochlroite (NaOCl). Comercial bleach solutions such as chlorox are typically a 6% w/v solution of NaOCl. In its solid form it is a sodium salt of hypochlorous acid. Because Sodium Hypochlorite is non-stociometric (i.e. it is not chemically balanced) it is unstable. In the solid form Sodium Hypochlorite will decompose at low temps i.e. 40 deg C. It is also unstable in solution and if you let it sit long enough or heat the solution to near boiling it will form NaCl and H2O. This tendency to decompose is why bleach is used in burn outs.

The burn out creates intense heat, through friction, which decomposes the bleach and liberates Chlorine gas (Cl2). The Chlorine gas almost immediately reacts with water vapor in the atmosphere to form Hydrogen Chloride gas (HCl, Also known as hydrochloric acid when dissolved in water). The HCl gas is the white smoke that you see during the burnout. If you ever open a bottle of hydrochloric acid blow into it. The vapor from your breath will create a large amount of white smoke when it reacts with HCl gas.

The chemical reaction would be;

2NaOCl + heat + (H2O)2 ----> 2NaOH + 2HCl + O2

So the short answer is, bleach is used in burn out contests because it produces a bunch of white smoke.

Drag racers today no longer use bleach, they simply use water. I also asked my Uncle Dennis who used to be technical director of Goodyear in Europe. He, in turn, asked Les Garbowicz who designed the Top Fuel Dragster slicks for Goodyear. Originally, the bleach and water solution was used because of the chemical pyrotechnic in the equation listed above. The idea was to burn off the top skin of the tire, "exposing the gooey tread rubber underneath". But they discovered that water would do just fine. As pure water is both cheaper and easier to handle, the chlorox was dropped.

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