Slow in, fast out

While I was reviewing the data set for the opening round of the 2018 Champ Car session I notice this significant spike in the fast lap for the 890.  Not only did none of the other racers produce a trace like this, but this trace was fairly unique for this racer also!  What did he do differently to be able to carry so much speed through turn 1?

To answer this question I turned to the video from the stint.  Linked here are these two laps; the RED lap and the BLUE lap. 

First thing we confirmed from the video is neither lap has traffic in turn 1.  Having the video along side the data is certainly a bonus.  

Next we looked at the longitudinal acceleration; where is the racer applying the brakes, how much is he applying the brakes, and when does he go back to throttle.  Below we will focus on just turn 1.  The top half of the graph shows the forward (longitudinal) acceleration of the car and the bottom graph shows the speed. 

For the red lap the braking begins earlier than the blue lap.  The gap between brake application, when measured in Race Studio (RS), is 75ft.  While traveling at 112mph you will cover 164.26ft in 1 second.  Between these two laps brake application happened about 1/2 second later in the blue lap.  

Next we look at the slopes of the deceleration lines.   Although minor in appearance, the blue line has a steeper slope than the red line.  The greater the slope the more aggressive the brake application and a greater percentage of weight shift to the forward tires.  The red line with its better weight distribution will have more grip available when turning begins and in theory be able to carry more speed and apply throttle sooner.  Looking at the traces it seems the racer did, in fact, feel there was more available grip as he began accelerating a full 32ft sooner on the red lap (measured in RS).  Further more the minimum speed for each lap in turn 1 was 82.2 mph and 76.8 mph respectively!  

By applying the brake 1/2 second sooner the racer felt he could carry nearly 6 mph more through turn 1 and get to throttle 32ft sooner!  That's massive! In fact this 1/2 sec sooner brake application related to a 1/2 sec gain for the red lap over the blue lap.  Slow in is FAST out! 

As we continue look at these two laps we see at least three other turns where the racer tries to gain time by late braking and in each case the results are the same, a slowed exit.

ACTION item

• Slow down, to go faster.  If you find yourself white knuckling at apex and unable to go to throttle, try backing up your braking point a fraction of a second and listen to your race car.  Does it tell you "I can take more throttle sooner"?  If it does then your braking point was too deep.

This was a great find when looking over this data.  Its a particular problem I wrestle with in my own driving.  Seeing the effect of late braking in the data so clearly will help me get faster, I hope it helps you get faster too!  Thanks Elon for the data and an oppertunity to critique your driving!