Robin Miller’s Mailbag for April 7, presented by Honda Racing / HPD

Robin Miller’s Mailbag for April 7, presented by Honda Racing / HPD

Insights & Analysis

Robin Miller’s Mailbag for April 7, presented by Honda Racing / HPD


Q: In your commentary on on March 29, you totally ignored the best Indy 500 on record – the 2013 race won by Tony Kanaan. There were 68 lead changes between 15 drivers, 133 consecutive green flag laps. Only five cautions for 21 laps. Nineteen cars finished on the lead lap. A record number of cars finishing/completing the most miles for the field. The final pass for the lead came two laps from the finish. Twenty-one individual records set in the race. All that while setting an Indy 500 mile record average speed of 187.433 mph, which still stands. Why did they change the rules after that? That was eight years ago, but there might be something worth looking at to get the cars back to where they were then.

Ron Rose, Peoria, AZ

RM: Mike Hull is always kind enough to help me answer questions out of my strike zone, and today he’s given us a history lesson that I intend to copy and paste for further use:

“Talked with the engineering group yesterday about your reader’s question about racing at the Indy 500 now eight years removed; here’s a long version/summation:

There are basically three things at play – aero configuration, track grip, and tires. The three act together to balance the mechanical and aerodynamic grip at Indy. Weather, car weight, engines, and other things have an effect too. The rules were pretty similar for 2012-2014: the DW12 aerokit with the bumper pods and beam wings in the rear. 2014 was not as good a race as 2013, but still pretty good as far as passes, cars on the lead lap, etc.

“In 2015 the manufacturer aerokits began, and while that was an amazing technical development time, it really did not improve the racing. During this period two other important things were happening, and the aerokits probably masked them. First, the track was getting older. As tracks age they lose mechanical grip as the surface gets more polished. The second thing is that materials for tires were being more regulated, especially exotic materials. We don’t know the details, but OSHA and other regulatory agencies worldwide clamped down on some of the chemicals used to make tires. It took a while for the tire manufacturers to develop compounds that regained the lost grip and durability, and some probably never came back.

IMS was last repaved in 2004, then it was ground in 2005. Grip was very high those years, but tire wear was extreme. Most probably remember the Formula 1 tire debacle of 2005. Other than some local grinding, little was done to the track until recently. It seems by 2013 the track was in a good balance of grip and tire wear (at least for IndyCar). The diamond grooves were still there, but the sharp corners seem to have been knocked off just enough, leaving a surface that had good grip, but did not destroy tires. Since then, the track grip has gone down a little each year. This probably isn’t evident from the outside, but the engineers can see it in the tire wear and temps as well as in the amount of downforce we have to run to stay flat.

So after years of reading about A.J., Mario and Langhorne in the Mailbag, we now learn that ‘the good old days’ were actually 2013. Image via IMS

In 2018 the manufacturer aerokits went away, and we went back to spec aerokits. Unfortunately, the tendency of the cars to flip in certain attitudes had come up during the aerokit era, and criteria had been set to limit the rollover and takeoff possibility in different attitudes. The bumper pods had also fallen out of favor, as they did not really prevent the cars getting airborne in car-to-car accidents. The new aerokit had to pass blow-over and roll-over criteria that did not exist in 2012.

The cars had also gotten heavier as various parts and reinforcements were added over the years. Speedway car weight in 2013 was 1550 lbs.  By 2018 it was up to 1590 lbs, and for 2021 we are now at 1655 lbs (the latest big increase offsetting the inclusion of the aeroscreen). A heavier car further limits how soft the tires can be made and still have them complete a stint; it also requires more downforce to get the car around the turns. When the car requires more downforce to perform, it naturally gets worse in the dirty air. Having cars grouped together gets harder and harder as the cars get heavier and the grip goes down.  

“In short, going back to 2012 is not an option, as the track is not the same and the cars have changed, largely for safety. What is needed is to add efficient downforce to increase grip while keeping speeds similar. The downforce also needs to be created so as to minimize the dirty air for following cars and also to perform well in dirty air. This is exactly why IndyCar has chosen to attack the latest aero changes by modifying the underwings. Their large surface area can create lots of downforce without making a lot of dirty air for the car behind, and is typically less affected in traffic than wings, sidepods, and other top-side aero. Without knowing race day weather, exactly how much track grip there will be, and a lot of other variables, it is a difficult bullseye to hit, but IndyCar is working hard with the team to enhance the quality of racing by making the target broader plus easier to hit.”

Q: The Pocono road course was used for professional races from 1973 to 1977:  IMSA Camel GT in 1973, 1976, and 1977; Formula 500 in 1973, 1975, and 1976.  I was at some of these and the crowd was small. But not as small as the World Series of Racing event you referenced. Pocono seemed to lose interest in road racing as NASCAR Winston Cup events became more popular.

David, Waxhaw, NC

RM: Thanks. Yeah, to be honest, Pocono was built for Indy cars and then NASCAR came along and road racing never figured in their equation for either. Wasn’t much of a road course as I recall, and certainly had limited viewing.