By Carlo Platella
The Balance of Performance is often a source of controversy and discontent in the world of endurance racing, with the risk of becoming even more so in a historical period in which the premier class also uses it. The IMSA championship decided to experiment with an innovative approach without changing the intervention parameters of the BoP, rather relying on a different strategy for data collection. The journalist reports it Marshall Pruett on the pages of Racer.comwhich explains how organizers are aiming for greater collaboration with houses during the process of formulating the BoP. “We wanted to do something different, that was based on trust and integrity”the words of IMSA president John Doonan.
Data collection for the BoP
The Balance of Performance is a necessary tool to balance the performance of cars with completely different characteristics. In fact, both between the GT and the Hypercar-LMDh, hybrid and combustion cars, with rear, front or all-wheel drive, powered by aspirated or turbocharged engines, as well as with different displacements and fractionations, compete. The most difficult task of the organizers is not so much to limit the performance of each car, but estimate its true potential.
The collection of technical and performance data of the cars is the basis of any Balance of Performance. Part of this information is the aerodynamic parameters measured during homologation in the wind tunnel, while the engine performance is monitored directly on the track thanks to torque and power sensors. However, the technical characteristics alone do not contain all the performance information of a car. Depending on the balance and general architecture, each car uses the tires differently, not to mention the inevitable discrepancies between the real aerodynamic values and those measured in the tunnel. It is therefore always supported by the technical characteristics a pool of data from the track.
Stopwatch problems
Real-world data is often collected in the form of lap times or in individual sectors, which however introduce a double problem. First of all, the overall time of a sector does not explain how it is achieved, as it cannot analyze the individual areas of performance: top speed, braking, entry, cornering and exit, reactivity, stability and balance. All this also varies with speeds, tire wear and fuel loads.
Added to this is the fact that lap times are also “contaminated” by the sporting aspect of car set-up and driver skill. In other words, it is not possible to trace the impact on the stopwatch of only technical characteristics such as weight, balance or aerodynamic load and resistance. Calculating BoP based on timing also encourages teams to hide the actual potential of the car in the testing phase, so as to enjoy more favorable parameters there when it really counts.
The IMSA plan
For the 2024 season the IMSA championship has decided to adopt a new approach to the BoP, currently limited to the GT classes only. It all starts from the dialogue that the organizers have held with the manufacturers in recent months, agreeing test programs together that returned data that was as representative as possible of the real potential of each car. Furthermore, in the recent collective tests at Daytona, the championship's technical commissioners worked closely with the personnel of each team, checking compliance with the agreed work plans.
IMSA technical manager Matt Kurdock explains to Racer.com: “After a full technical inspection of the cars, our scrutineers work within the teams as they complete their test programmes. We check various aspects, including which tires are on the car or that the petrol loads are as prescribed and other similar things. During my time here and having been involved in other previous tests, I don't think this has ever been done on this scale.”
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The Daytona test
At Daytona each manufacturer designated a team and a driver with which to complete the work programs for data collection for the BoP. These included three runs of 5 qualifying simulation laps each and one complete race stint of 28 laps. Each car theoretically ran to its maximum potential, allowing for more elaborate information gathering than lap times alone. The data collected will also be shared with all manufacturers, who will compare and check each other to identify any anomalies.
“IMSA is trying to cover up all aspects that could hide potential of a car and we are not naive”, explains Kurdock. In fact, before estimating the performance of individual cars and calculating the BoP, the data will be analyzed to first and foremost ensure that they are representative. From an overly conservative driver's driving style to deliberately underperforming tuning, there is no shortage of tools with which manufacturers could theoretically hide.
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However, like any rule that needs to be respected, IMSA also has a deterrent in store. In fact, the regulation allows the exclusion of a manufacturer from the race if its performances in the race are excessively superior to those expressed during the testing phase. At the moment the new approach is limited to the GTD and GTD Pro classes. If successful, however, it would not be a surprise if IMSA decided to replicate what was done in the GTP class as well, with the possibility that the WEC could also draw inspiration from it for the own Balance of Performance.
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