Monday, May 16, 2011

Race Strategy - Indy 500 compared to Rolex GT

The May 2011 issue of Racecar Engineering recently arrived in the mail. The cover promised that Andy Brown, Target Ganassi engineer, would reveal the secrets of Indy 500 race-winning strategy calls. I opened it right up and read the article with interest, having made race strategy calls in ALMS and Grand Am for the past 11 seasons.

Now, I’m not normally one for comparisons – my dog is meaner than yours, my car is faster than yours, and so on. And I don’t know if Andy told it all, or just the parts that he thought would be obvious enough that his competitors would have already figured them out. Also, I don’t have recent experience with the Indycar rules and race control procedures, so I’m assuming everything relevant from them is factored into Andy’s strategy calls.

But, I gotta tell you, it sure looks equally, if not more, challenging to call a GT class car in a Grand Am Rolex race than it does to call the Indy 500. Here’s why:

Number of sets of tires
Indy 500 – Limited number of tire sets
Rolex GT – Limited number of tire sets
Comparison – Neither series seriously cramps your style on race day, unless things get weird. Same for both.

Tire performance
Indy 500 – Tires wear out in slightly more than one stint. No performance falloff over the stint.
Rolex GT – Tires don’t wear out. Performance falls off considerably over the stint.
Comparison – The end result is similar.
There is a “drop dead” point in a fuel stint for either series, beyond which you must change tires. Rule of thumb applies for a relatively easy call during the race.

Race length
Indy 500 – 200 laps, and that’s that.
You know exactly how many laps remain, but the timing, number, and duration of caution periods will affect your strategy.
Rolex GT – All races by time, not by number of laps
You can calculate how many laps remain, IF the remainder of the race stays green. If there are yellows, the number of laps remaining reduces, since a pace car laps takes more time than a green race lap.
Comparison – Rolex is tougher
Yellow flag laps save fuel AND reduce the number of laps remaining. So, you have a moving target. If you wait until you are clearly in the window to the end of the race before pitting, you will likely give up track position to those who gambled and pitted prior to the window, counting on being saved by a yellow or two before the finish. But, how early is too early? And what if there isn’t a yellow to save you, and now you have to stop for a splash to make it to the end, giving up track position? No easy answers…

Green flag pit stops
Indy 500 – You lose a lap
So, it’s fairly straightforward. You try to avoid intentionally forcing yourself to pit under green.
Rolex GT – You may lose a lap. Then again, you may not.
It depends on how long a green flag lap takes, which in turn is depends on both track length and average speed. It also depends on how long the pit lane is and how fast the past car goes. And, it depends on whether you need a full fuel fill or partial, and whether you must change tires or not. So, it may be a sin to stop under green, or it may be an advantage, depending on the situation.
Comparison – Rolex is tougher
Any time you can set a “rule of thumb”, that’s one less thing to worry about during the race. And, even at little bullrings like Barber, there’s no sure rule of thumb for Rolex green flag stops.

Pace car waveby
Indy 500 – Leader restarts first. Cars between leader and pace car waved by. Pits closed.
You can forego a pit stop if circumstances lead you to expect a waveby. Useful to get back on the lead lap, if you don't lose it again with a green flag stop shortly afterward.
Rolex GT – DP leader restarts first. Cars between pace car and leader waved by. Pits open.
Here’s a critical distinction. The “GT” leader can indeed take the waveby, if in front of the DP leader, thereby gaining nearly a full lap on any GT cars that do not take the waveby. ALMS used to do this too, but they changed their rules a couple of seasons ago to avoid creating this situation. And, the pits are open, so you can also make a pit stop, if you think you can beat the pace car around, then pit and get out before the pack arrives. The waveby is on the final lap of caution, though, and there won’t be time to pit AND catch the field. Not to mention the increased risk if something goes wrong during the pit stop. High stakes, high rewards, quick decisions
Comparison – Rolex GT is tougher
Tougher than Indy, and tougher than DP, too. Whenever the race leader can get a waveby, the stakes are high.

Indy 500 - Park it
Rolex GT - Keep going
Comparison - You've got to decide when to switch to wet tires and when to switch to back to dry tires, and whether to do this under green or wait for the nearly inevitable caution. Then, there's the question of how thoroughly do you convert the setup to wet specs, and whether to make any of these changes during a pit stop. And finally, there's a lot of dependence on driver comments.

Reading what I've written, I'm afraid you'd conclude that I'm saying the lot of the Rolex GT race strategist is tougher than that of the Indy 500 strategist. I seriously doubt that is true, and that's not my intent, as I said at the start. They are competing against teams with deep specialized experience in a unique event. There is little margin for error, or even for good, but not optimum, strategy calls. Meanwhile, endurance road racing has a certain amount of fuzziness that can compensate for these same good, but not optimum calls. Apples and oranges...

Still, I think it's pretty clear that calling strategy for a GT car in a garden-variety Rolex race is at least as challenging a calling the 500. And that was a bit of a surprise to me when I read Andy's article.

Special thanks to Andy Brown for opening up on this subject, one that most race engineers, team managers, and other race strategists would rather not discuss.


  1. I don't know who told you that Indy 500 tires don't fall off over a stint, but they were wrong. It's muddled because of the draft and fuel load, but it is significant.

    You make good points, and I agree that a Rolex GT car strategy is more complicated. But I wouldn't say it's more difficult for two reasons. One, an oval race is so much more hectic. A two minute lap is much easier to make a call for a fuel stop than a 40 second lap where you use only about 0.3 of a gallon on an inlap. Going one more lap at Indy can be huge but always a big risk, and you get about 20 seconds to make the call. And the second reason is, the stakes are much higher than any GT race, including the 24 hrs.

  2. CP - The tire falloff assessment was Andy Brown's, in his article in RCE. Took him at his word.

    Your point about the hectic pace of an oval race is valid. I cut my teeth on race strategy in the IRL. My first sports car season was with Riley & Scott on the Cadillac LMP. Before our first race, I told Bill Riley I was a little concerned about the strategy calls. His response went something like this - "You're used to making IRL pit calls. You've got, what, 20 seconds to decide? You'll do fine".

    Like I said at the start, I don't like making comparisons.

  3. After I posted I thought you might have gotten it from RCE. I haven't read the article, but that is very surprising. Tire deg is something you see even in qualifying, a four lap run at Indy. Magazines often mis quote and get things wrong in my experience, so maybe that is what happened. I ran Indy last year and I think they are bringing the same tire again.

  4. What is the path to become a racing team engineer ? Where do you start from? Do teams sign with people that have education in physics but no experience in setting up a real car? How do you gain such experience? Does sim racing help?

  5. Mertol, any beginner positions these days pretty much require at least some sort of racing-related experience. Either a degree from one of the schools that offers motorsports curriculum, Formula SAE participation, real hands-on racing experience, or more are needed. You have to have something to offer, even as a beginner. Race teams aren't in business to train engineers, they're in business to race. My own background is a little unusual. I have a BSME and worked in computer applications for engineers while I built and drove my own car in SCCA club racing, learning the race car engineering as I went. Data acquisition was an easy entry point for me, since I knew computers, software, cars, and driving. It's still a good starting point for a beginning engineer.

  6. Hey I know computers and software too in fact I have a degree in computer systems and technologies, but have only virtual racing experience :(.