| | |  | | Bobby Labonte is setting the pace in points, but NASCAR felt his Pontiac was still aerodynamically behind the Fords and Chevys.
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Starting this weekend in Michigan, the Pontiac Grand Prix race car will have a new bumper cover. The freshly manufactured piece will greatly change the aerodynamics of the body style.
Now, I know what you are thinking. "If the Pontiac was so bad, how is it that Ward Burton, Bobby Labonte and Tony Stewart have all won races?" You might also remember that Johnny Benson almost won the Daytona 500 in a Pontiac.
Well, NASCAR races on so many different kinds of tracks that down force is very important at some events, while not so important the next. All the aforementioned drivers also have very good teams and any given week anyone can win, as is very evident this season with 12 different winners in 13 races.
So, why the change 12 races into the season? Well, from the start of the 2000 NASCAR Winston Cup season, it has been apparent that the Pontiac had less down force than the newly redesigned Chevy Monte Carlo and the reworked Ford Taurus.
It had become obvious to NASCAR that Pontiac was at a disadvantage. The numbers told officials as much. The Grand Prix was behind by between 165 to 200 pounds of down force in the rear compared to Chevy and Ford.
Aerodynamics is a very hard thing to understand, because every little change can affect a different aspect of the car. A quarter of an inch up or down on the front valence can change the down force on the back of the car by 65 to 70 pounds.
One little strip on the roofline may make the difference of whether the car will roll 20 times down the front stretch at Talladega, or stay upright and in control of the driver. Teams spend hundreds of thousands of dollars testing very minor changes on cars to search for that perfect balance.
There are three main changes to the Pontiac's tail section to look at during qualifying Friday and Sunday's Kmart 400. First, the bottom of the bumper is now about one inch higher off the ground than before. And, while the very top of the spoiler is still in the same position, and the lower edge of the deck lid is still the same, it is like they got out a file and began shaving away an inch off the bottom of the old bumper.
The second change is that the side edge of the top of the bumper cover is now about five inches longer down the side. This is hard to explain if you are not looking at the piece, but it is kind of like someone went crazy with Bondo and made an entirely different taillight than on the original design.
The biggest change is that the bottom corner of the tail section is now a sharp right hand corner, squared off and not rounded. This changes the airflow around the back of the car greatly.
The simple science of this rule change is that the air going down the side of the car will be directed straight back away from the car much more now than before. As the air rushes away from the back of the car a negative pressure is created right behind the rear spoiler. This negative pressure sucks the air coming off the top of the car down into the area right behind the car. This adds pressure on the spoiler and creates down force, which helps keep the car glued to the track.
The old bumper cover let a great deal of air swirl behind the trunk and created more high pressure which pushed some air up away from the spoiler and sacrificed down force.
Michigan Speedway will be a very good test of how equal the cars are now on this type of track. The wide corners often allow for caution free racing. You might remember that the first race at MIS in 1999 was the worst race of the season. Very boring. Goodyear began to implement its new generation tire for the second event their and that made a great deal of difference.
NASCAR is very concerned with having the different manufactures as equal as possible. I am glad they made this change. With cars that are as close to equal, we will get to see how really is the best team.
The politics between the teams and the manufactures will always be the same: "They have an advantage by (blah blah blah)." That is the nature of this game.
Just remember that next year Dodge joins the fray and then there will be one more guy to point a finger at! | |
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AUDIO/VIDEO
 ESPN's Ray Dunlap takes a look at the changes made to Winston Cup Pontiacs.
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