Sit back, grab yourself a cup or glass of your favorite beverage, and have a listen to the story of how I learned about the importance of braking, corner speed, acceleration, and a few other things.
Back in 1999 and 2000, I was coaching a driver who was competing in the North American Formula Atlantic Series, one of the steps on the ladder to Indy car. There were twelve races on the series calendar, from Long Beach to the Milwaukee oval, and Road America to the street course at Trois Rivieres.
This was relatively early days of data, but we had the latest Pi system in the Atlantic car, and I loved digging into it. I’d stare at data graphs for hours, thinking about how the shape of the speed, throttle, brake, and steering angle traces related to one another. The more I learned, the more questions I had, such as:
There were dozens more questions rattling around in my head, but the main one was how I could use existing data to calculate the effects of various changes in driving technique. I spent the following week staring at an Excel spreadsheet that I had created and imported data into from the Pi system.
Starting with the shortest circuit we’d run all season, Trois Rivieres, I had columns of data for lap distance (in feet), steering angle, throttle position, brake pressure, and speed (in MPH). From this I’d identify where a brake zone began and ended, where the corner began and ended, and where acceleration began and ended. This resulted in 644 rows of data correlated to 7,852 feet of track.
Then came the real fun, educational stuff. And harder work.
I added seventeen more columns to the right. In each one, I created a different “driving scenario,” and then manually manipulated the data to suit: braking one car length later for a corner; getting to full throttle a car length earlier; carrying one MPH more min speed through a corner; and/or some combination of these.
Fortunately, Trois Rivieres only has seven corners, so this took just a day to work through all seventeen scenarios.
Overall, my goal was to find the priorities—where should my driver focus his attention to find the most gain in lap time? Is braking later going to save more time than beginning to accelerate sooner; would carrying a bit more speed through the corners help more; what’s the benefit of focusing on exit speed?
With each scenario, the formulas I had built in Excel would calculate the overall lap time, and, therefore, I could see what the individual scenarios would do. As you can imagine, what was faster in some corners wasn’t as effective in others, mostly depending on the radius and speed of the corners, and how long the straights were before and after them. And I should mention that I’m skimming over many of the details of how I manipulated the data in a logical way (and that I learned a lot about what not to do in an exercise like this!)
The results were fascinating, and have had a long-term effect on my thinking about driving.
To make sure that what I learned from this exercise didn’t only apply to short street circuits, I then tackled Road America, the longest circuit we would be racing at that season. With 4.05 miles (21308 feet), eleven corners, and a greater variance in corner speed, I expected some different conclusions.
Actually, the key take-aways from this exercise did not vary much at all between Trois Rivieres’s tight street layout and Road America’s long straights and sweeping turns.
I’m guessing you’re on the edge of your seat wondering what these key take-aways were! Well, that’s top secret, and I’ll never share it with anyone for less than “one million dollars” (said with my best Dr. Evil imitation).
Well okay, you did pay good money to subscribe to my Driving Directions, so that’s pretty close to one million dollars, isn’t it? No? Hmmmm… okay, here I go, anyway. Here are the main take-aways.
The biggest difference in lap time was an increase in minimum speed. One MPH more through a corner, even if you began braking and accelerating in the same place, resulted in an average of half a second. Braking later by what would be a difficult-to-achieve amount (depending on brake zone length) typically averaged in less than two-tenths of a second improvement. Exit speed was slightly more important (most of the time, but not all), but not as important as corner min speed.
I should also mention that I did try going too far with all the scenarios, and the one that had the biggest negative impact was carrying too much min speed. So, there’s a delicate balance between too little and too much. But you knew that already.
Beginning to accelerate from one MPH resulted in a bigger gain than applying the throttle much earlier (but from the original min speed). This was especially true with Road America’s long straights. I was surprised by the difference, and spent a lot of time trying many scenarios to see if I could reverse that finding. Later, I even tried it at other tracks, with some version of the same take-away.
Like any data, it’s how you interpret it that matters. I’m sure I could have found a way to show that later braking was the best option, but I just went thought what I thought were reasonable variations of driving technique, based on my experience. That’s why I refer to what I learned as “take-aways,” and not rules or even guidelines. I strongly believe that they work more than fifty-one percent of the time, but I’d be surprised if they were the way to go ninety percent of the time. So, there will be exceptions.
I should mention that this was based on an open-wheel car, but not a super high-powered one (like an Indy car), nor a low-powered one (like a Formula Vee). Could it be different for a production car? Yes. However, I have done the same exercise with a GT3 car, and the take-aways were similar.
Also—and this is extremely important—the drivers with whom I have done this exercise have all been experienced, good, what you’d call (at least) “fast” drivers. So, if a driver was braking waaay early now, I suspect there would be more to be gained by compressing the brake zone more than corner min speed; if a driver was over-slowing a lot, then min speed improvements would show as being an even higher priority; if a driver was lazy or hesitant accelerating out of corners, then that would be the low hanging fruit to go after first.
Again, whenever I’ve done this, I’ve based it off a good driver. Still, the driver that I first used this approach with—the Formula Atlantic driver—did pick up a relatively large improvement in lap times. For example, by focusing on what we learned from this exercise, he lowered his lap times by nearly a second at Road America. While he was a good, fast driver, there was still a chunk of time to be gained.
Until we used this approach, his go-to driving technique to try to improve his lap times was simply to brake later. He did make some small improvements by doing so, but he gained more by braking lighter or releasing the pedal slightly earlier in some corners.
I said previously that this exercise has had a long-term effect on my thinking about driving. To make sure that I’m not missing something with more modern cars, I’ve revisited this more than once over the past twenty-five years. While there have been some minor changes in the results, I’d say that 95 percent of the lessons have not changed. Apparently, the laws of physics haven’t changed very much in the past quarter of a century!
How have I used these take-aways? When I look at data and what a driver is doing, and prioritize my thinking in terms of what to do to go faster, this often biases my approach. And I don’t mean bias in a bad way. I mean it helps me quickly think about where to start looking for improvements.
Again, I’m not saying you should never work on braking later, or even getting to full throttle sooner. You definitely should. What I’m saying is that trying a slightly lighter brake (BoB and EoB staying the same) to increase your min speed might be more valuable.
Something to think about, right?