Burnouts in drag racing

The other day, while doing some research on Greg Anderson's engine mishap at the Texas Motor Speedway earlier this year, which video was quickly removed from YouTube, I came across an article on "Burnouts: An Appreciation", by Car and Driver.

A pro stock doing a fiery burnout

Below some thoughts on the subject along with some quotes from the Car & Driver article.

Burnouts are a function of our modern day selfish society, for there is nothing more antisocial then doing a burnout in an inappropriate place, especially in your church's parking lot or while on tour with your old timer's club (WABI). But we all understand why it is done, for it is arguably the most fun you can have with friction while keeping your ants on!

"Tires will smoke when you reach the point of volatility or vaporization of the materials in the thread compound," says Goodyear race-tire engineer Robert Bethea.

"It is important to remember that one purpose of a burnout is to remove foreign matter [such as might be collected while rolling around in the pits]," explains Bryce Jones, Goodyear's sales-account manager for drag racing. "There's no standard optimum temperature for the surface of the tread to reach during a burnout.....You could safely estimate the tread's temperature at about 400 degrees immediately following the burnout but even that depends upon the length of the burnout. john Force, for example, prefers a long, hard burnout."

After the burnout the tire temperature will drop quickly so its important to stage for the competitive run as quickly as possible. "We don't have a set temperature," says Greg Anderson, the four-time NHRA Pro Stock champion. "We're usually in the 120-140-degree range."

"We try and repeat the same burnout and length every time," explains Anderson, and depending on the tackiness of the track and weather conditions, that means performing the burnout between 7000 and 8000 rpm. "If it is really sticky, you can get away with 7000 rpm. We get the tires spinning to the rpm we want, and then we'll release the line lock.

Finally, a goal of drag racers is laying down a fresh coat of rubber on the track for their slick [tires] to bite into. "Everyone leaves with their tires in the same spot," continues Anderson. "It's more important now that every car has the same 105-inch wheelbase. There's a bald spot right there where everyone launches. We try to put rubber over that bald spot."

Thanks for reading.

Source: Car & Driver.
Photo credit: Whathehell Racing Team (Pontiac Firebird)