Thursday, July 25, 2013

Is another track record in store for this weekend's Brickyard 400?

The new Gen-6 car is fast. But how fast? 2013 is the first season with the new car, and we keep hearing how speeds have picked up, breaking track records several times this season.

Today we investigate how much faster this new car is, considering if it does better on certain tracks than others. We'll use that data to predict what the pole-winning speed could be at this weekend's Brickyard 400 in Indianapolis.

The chart below shows the increase in speeds so far in 2013 compared to the same races last year:

The huge jump at Kansas is due to a repaved track surface. This gain would have happened whether or not we had a new car.  Excluding Kansas, here is what we see:

The average jump in pole speed at these tracks is 1.7mph, or 1.1% above the speeds from last year. Twelve tracks saw faster speeds, while three tracks saw drops. The minimum positive gain is 1.0 mph. 

The tracks with reduced pole speeds were Sonoma, Dover, and Michigan.  These tracks are all so different (road course, intermediate, and superspeedway). There is no trend here. The tracks with the biggest gains were Fort Worth, Bristol, Charlotte, and Loudon.  Again, these are very different tracks. The data suggests that improvement in track speed is happening because of the car, not because of any particular type of track.

Let's keep going with our analysis. Below are the improvements in pole speeds from 2011 to 2012, both of these years using the previous Gen-5 car.

Again, the biggest gains are due to track repavings.  Removing the outliers (above 3 mph), here is what remains:

This chart shows that twelve tracks saw a pole speed increase, while almost the same number, eleven, saw a decrease.  The net average change was 0.1 mph, or practically zero. This indicates that the new car is responsible for a meaningful difference in speed.  A normal year would show almost no change in speed, but the new car caused an increase of 1.7 mph. We know this trend can't continue forever.  20 years of 1.7 mph increases would be a 34 mph jump. NASCAR would never allow the cars to get that fast. (Or would they?)

As we have seen above, consider that the biggest effect to speed increases have come from track repavings.  On average, a fresh track surface can increase speeds by 10-15 mph. This factor is ten times bigger than the effect of a new car.

Turning to this weekend's Brickyard 400, what can we predict about the pole speed?

Here is the full history of pole speeds at this track:

Remember that every year there are minor changes in rules, equipment, and tires, along with gradual wear and tear in track conditions. Notice the rapid growth in the first ten years (13.9 mph gain) before dropping 4.5 mph in 4 years, and then settling in the 182/183 range.  

The pole speeds in the last two years were:
182.99 mph in 2011
182.76 mph in 2012

That's a drop of 0.23 mph.

By considering the tracks that had similar drops in 2012 and looking at how those tracks have fared in 2013, we can expect an improvement in speed this year between 1.07 and 2.16 mph.

That would allow us to predict a pole speed this weekend in the range of 183.84 to 184.92 mph.

The track record is above 186 mph (set in 2004), so we should *NOT* expect to see a track record this weekend.

Let's see how accurate this prediction turns out to be. If I am wrong, you get your money back.