In addition to the difference of the class itself between GT500 and GT300, there are over 40 different car models competing in SUPER GT. Engine power (horsepower), shape of the car, and tires are different, and the performance is uneven, but there are always intense and close battles on the track. This is realized because SUPER GT’s unique rules, Success weight and BoP (Balance of Performance), are effective. In this series, we heard from SUPER GT’s Data Inspector (DI), Isamu Komiyama, and Technical Advisor (TAD), Hiroshi Kato, about BoP.
>Go to Review: “Success weight” and “BoP” (Part 1)
Isamu Komiyama, SUPER GT Data Inspector
Became SUPER GT Data Inspector in 2017 after resigning from a car manufacturer. Komiyama is responsible for collecting and analyzing vehicle data of all cars after qualifying and race and provide it to SRO and GTA. He also chairs the adjustment of performance committee of GTA.
Hiroshi Kato, SUPER GT Technical Advisor
After experiencing various roles at different teams, Kato assumed SUPER GT Technical Advisor in 2024. He is involved in the entire technical domain including the technical part of the sporting regulations, adjustment of performance, etc., and provides support to the technical team. Kato is a member of the adjustment of performance committee.
BoP (Balance of Performance) is a method used to adjust the difference in speed between GT500 and GT300, as described before, and defined in the regulations to equalize the GT300 race cars consisting of 13 car models that compete in the series. Adjustment points specified in BoP are broad and complicated. It may seem to be better and simple to adjust the output of the engine to align all cars to have 300 horsepower, but why is it not done so?
“There are 13 different car models participating in GT300 (this year). All cars have different shapes. So, the air resistance is different also. Engines mounted on the cars are different too, so the displacement as well as characteristics are also different. In addition, the tires are multi-make in SUPER GT and a wide variety of tire manufacturers are supplying tires. If these became all the same, then standardizing to 300 horsepower could be a possible option, but, then, that would be just a one-make race. That is why BoP is effectively used for balancing so that the characteristics of race cars and tires would be preserved. BoP is an abbreviation for Balance of Performance, which is sometimes interpreted as performance adjustment, but strictly speaking, that is not equal. English term of Performance includes race car, engine, tire, driver’s ability, team’s ability, etc., and BoP balances out all of these.
Also, some people mix up Success weight and BoP, but Success weight is a handicap given to individual car based on the result so that it would be difficult for the same car to obtain good results continuously, which would even out the race. In some situations, it can reverse the positions (because the original speed is suppressed). BoP, on the other hand, is, as said before, adjustments for each car model to enable different car models that compete in GT300 class to fight on the same battlefield, and also to squeeze the gap so that vast variety of car models can compete together. For example, the role of BoP is to make 5 second gap between first and second places to 0.5 second. To reduce all gaps without changing the position is what we are aiming for. Simply speaking, we want to see all cars lined up side by side when the checkered flag is waived, like in horse racing. That can be within 1 second or 0.7 second… the target value is decided based on the circuit, weather, etc., but we want to put all cars in that small gap”. (TAD Kato)
BoP issued exclusively for SUPER GT by SRO and Requirements (BoP) actually published for Round 2.
BoP published as Requirements for participation at every race specifies minimum weight, air restrictor diameter, BoP weight, minimum ground clearance(*), refueling restrictor, and maximum boost pressure (for turbo car only) to achieve a balance among different car models by controlling the motion performance and engine power of race cars, which are referred as ‘Stop’, ‘Turn’, and ‘Accelerate’. *Adjustment is achieved by minimum ground clearance for FIA-GT3 and skid block spacer thickness for GT-GT300.
SRO, the promoter of GT World Challenge and Inter Continental GT Challenge, is significantly involved with the decision process, and the details are decided along with GTA’s Adjustment of performance committee chaired by DI Komiyama which then conveyed to the entrants. (It is also posted on the official website of SUPER GT.【Round 2 Fuji】 Requirements (BoP etc.,) for each car for Round 2 Fuji)）
“Process flow until finalization of BoP starts from providing the data collected by GTA and a view of the adjustment of performance committee to SRO and request them to determine BoP for FIA-GT3 race cars. We provide a consolidation of data of all cars (best lap time, maximum speed, etc.) that GTA collected after the qualifying and race”. (DI Komiyama)
DI Komiyama collects data from all cars after the qualifying and race, refines them, and then sends them to SRO. SRO and GTA finalize BoP after that.
“GTA conveys SUPER GT’s unique conditions and environments such as the characteristics and weather of the circuit that hosts the race, performance difference between tire manufacturers, analysis of the data collected by DI Komiyama, etc. After SRO reviews data and creates BoP for GT3, ‘GTA-GT300’ and ‘GT300MC (Mother-chassis)’ portions governed by GTA are added. Representatives of SRO visit Japan a few times in a year during an official test or race, so we exchange opinions there too”. (TAD Kato)
In the review of data done by SRO and GTA, they do not just look at recent tests or races but they sometimes go back to races from previous year or even before that. In another words, it is not something that can be decided only with recent data. For the FIA-GT, there is also categorization for track (circuit), for example, track like Fuji Speedway with a long straightaway or circuits with many turns like Okayama and SUGO, which is used for making more granular adjustment based on the characteristics of the circuit.
“We subtract the time spent for pit stop or problem solving and the effect of success weight from the total time of race to find out the actual speed of the cars, the speed of each car model, which are plotted on a distribution graph. And then we find the median after dropping the furthest deviation from each end, which becomes the target baseline. We keep track of the trend of the deviation value over a long time. The value is not something that would change after one race, so we keep on repeating the exercise. Therefore, this is not something that can be decided easily. Decision must be made by combining facts from physics and statistics. Documents we receive from SRO are only on the FIA-GT3 and written in English, so we first translate it to Japanese and then simply add ‘GTA-GT300’ and ‘GT300MC’, which we manage, therefore, basically, we do not make any changes. The base of BoP for the FIA-GT3 is decided by SRO”. (TAD Kato)
Collect as many data as possible over a long time, review and consolidate them, and analyze the data at granular level to identify a numeric value —- it sounds like a mind-blowing story, but the members of adjustment of performance committee put that much of efforts to create ‘BoP’ so that SUPER GT can be competed more fairly. Their efforts are directly linked with SUPER GT’s ‘Attraction’,’Thrill’, and ‘Excitement’. Exploring success weight rules and BoP further can increase the level of your enjoyment of SUPER GT.
≫ Requirements (BoP etc.,) for each car for Round 1 Okayama
≫ Requirements (BoP etc.,) for each car for Round 2 Fuji
