Now that we’ve established what the goals are with BoP, let’s look at the tools IMSA uses to get there.
The first tool is timing and scoring scoring data. In the earliest days, this was the one and only mechanism used to establish BoP.
The fastest cars on the time charts generally received more mass or perhaps a smaller air restrictor in the engine to reduce horsepower. Slower cars had mass removed and/or larger restrictors, and in a perfect world, every car met in the middle. For cars with turbocharged engines, upward and downward changes in boost pressures were made.
Unfortunately, strictly looking at timing and scoring data was not enough. Again, we’re talking about cars that in many cases are radically different from others they’re competing against.
And while they may be close in overall lap time, how each car achieves that lap time can vary. Cars can be faster on straightaways and slower through turns and vice versa. If that’s the case, one car could have an insurmountable advantage over others depending on track configuration and characteristics.
Also, when you combine highly professional race teams and drivers and world class manufacturers, they’re all looking for the slightest BoP advantage they can get. They mastered the art of masking their car’s true performance from a Timing & Scoring perspective long ago.
That led to the introduction of a new tool for IMSA to use in BoP, the independent data loggers now installed on every car. These loggers provide a much more complete and unfiltered picture of each car’s performance.
Along with the implementation of data loggers came the introduction of the eight-person IMSA Technical Committee (ITC). Members of the ITC carefully analyze timing and scoring results and data from the loggers immediately following each race and produce reports with any recommended adjustments based on each car model’s observed performance.
Once the ITC’s post-race analysis has been completed, conference calls and online presentations are held with all manufacturers in each class. This provides a forum for the manufacturers to present any BoP issues that their own data and post-race analysis may suggest and to see how cars from other manufacturers are performing in their class.
After thorough analysis, meetings and presentations, the ITC meets a final time to establish the BoP for the next event. BoP tables are published no later than seven days prior to the first day of official on-track activity for each event.
Common BoP changes include adding or removing mass, changing the size of the air restrictor for normally aspirated engines or boost pressures for turbocharged engines, or changing maximum RPMs. In the DPi class, BoP changes also may be made to a model’s aerodynamic configuration.
Fuel capacity is another tightly controlled variable through BoP to ensure similar stint lengths for each car in a class. In addition, fuel flow restrictors and autonomous pit lane fuel take sensors are used to measure refueling times and ensure that each class’ minimum full-tank refueling time regulation is not violated.
On the day after the Motul Petit Le Mans wrapped up the IMSA WeatherTech SportsCar Championship, IMSA hosted a collaborative meeting with all participating manufacturers to solicit their feedback related to improving the BoP process for 2020.
A follow-up meeting earlier this month led to revised BoP regulations. It reaffirms IMSA’s data-driven process, while at the same time introducing more human oversight of the ITC at the request of the manufacturers.
“IMSA and our OEM partners share the common goal of providing the most competitive form of sports car racing for IMSA fans,” said IMSA President John Doonan. “The IMSA Balance of Performance process continues to evolve to ensure the core competitive elements of IMSA sports car racing provide the necessary entertainment and value to our audience and stakeholders.
“The IMSA Technical Committee has worked tirelessly on these modifications for 2020 and it should make for close and competitive racing throughout the season.”
The revised regulation has been detailed in the 2020 IMSA Sporting Regulations for both the WeatherTech Championship and Michelin Pilot Challenge. The ITC will introduce a new metric aimed a better representing a car’s overall pace during a stint known as the “Weighted Sorted Sector Lap” (WSSL).
The WSSL uses a larger percentage of a car’s demonstrated performance and will be used to compliment the previously used “Weighted Eclectic Lap” (WECL), which mainly focuses around peak performance.
IMSA also will continue to utilize recorded wind tunnel data, engine dyno data and logged car data as a reference to monitor the performance of all cars within each specific class. Fuel consumption and fuel flow also will continue to be closely monitored to ensure stint-length compatibility, allowing teams to make the difference based on their choices to run full-rich or save fuel during the race.
The specific and unique nature of the 3.56-mile Daytona Int’l Speedway circuit requires a unique approach to BoP for the Roar Before the Rolex 24 on Jan. 3-5 as well as for the Rolex 24 At Daytona event weekend on Jan. 23-27.
The starting BoP tables for Daytona released today have been based upon the ITC’s post-race analysis and corrected BoP from the 2019 Rolex 24 At Daytona. Race performance metrics were generated by the best example of each manufacturer’s car in dry conditions. Wet weather performance also was analyzed but did not play a role in the 2020 Daytona BoP.
For the DPi class, performance will remain at the same median class level as the 2019 Rolex 24 At Daytona. In GTLM, the BMW M8 GTE will serve as the baseline performance level due to the introduction of new homologations for the Corvette C8.R and Porsche 911 RSR.
To establish BoP for those new models, a combination of FIA/ACO wind tunnel and dyno testing data and subsequent IMSA aero and dyno testing validation was used.
In the GTD class, a small, class-wide reduction in lap-time performance will be implemented through reductions in power and mass. The main goal, driven by manufacturer and team feedback, is to address previous top-speed interactions between GTLM and GTD cars.
IMSA expects these reductions will result in even closer competition within each class. In addition, the reduction in mass for GTD cars is expected to better align tire degradation over the course of a stint for all cars regardless of mass. These changes were successfully validated during November’s Michelin IMSA SportsCar Encore at Sebring International Raceway in November.
Starting with BoP for the March 21 Mobil 1 Twelve Hours of Sebring Presented by Advance Auto Parts, the ITC will analyze data from each 2019 WeatherTech Championship event as generated by the best example of each manufacturer’s car.
Once the BoP for all 2019 events, excluding Daytona, have been corrected, the ITC will take these track, manufacturer and class-specific values and calculate a season-long average. This calculation, in addition to any other available data, will be used to establish the starting BoP for Sebring.
Based on the experience of 2019, along with stakeholder and manufacturer input and necessary process analysis, IMSA and its manufacturer partners agree this approach provides for any 2019 season-long development will be effectively captured.
The end result is expected to enable teams and drivers – and not BoP – to determine the outcome of every race.