This weekend’s first round of the 2021 Autobacs Super GT Series, taking place at Okayama International Circuit, will feature a special Balance of Performance (BoP) in an attempt to control speeds in the series’ first race at the venue since 2019.
All GT500 cars will have the fuel flow rate reduced from the standard rate of 95 kilogrammes per hour, down to 90.2 kg/h, with the intent of reducing horsepower and top speeds.
The cars in the GT300 class, on the other hand, will carry additional BoP weight on top of the “standard” BoP weight as set by the GTA and SRO, again with the intent of reducing their speed. The additional vehicle weight will vary from 33 to 52 kg, depending on the model.
These BoP changes were trialed by all teams during the first official pre-season test at Okayama on 6-7 March, and were effective in their intent – with the fastest times in testing being about 1.5 seconds slower than the official GT500 and GT300 lap records set at Okayama during qualifying for the 2019 race.
This is the first time that the 2020-spec “Class 1+ɑ” vehicles will have raced at the venue, after the COVID-19 pandemic forced Okayama, Autopolis, and Sportsland Sugo to withdraw from last year’s calendar. Okayama has also expanded the run-off area at Williams Corner (Turn 2) and the Moss S-Curves last year, but the 3.7 kilometre track still has some of the narrowest runoff areas of any of Japan’s six major motor racing circuits.
As confirmed during the March test, all teams will be mandated to change four tyres and drivers during their routine pit stop in order to meet the regulations for this race, as well as in the season finale to be held at Fuji Speedway on 28 November.
This rule was introduced for the second round at Fuji last August, as a safety precaution following a number of tyre failures in the opening round. The compulsory four-tyre exchange was then dropped for the remaining rounds of 2020.
The rule has now been reintroduced as more of a competitive measure, and will have the greatest impact in GT300 – where several teams have been able to gain track position in races by changing only two tyres, or not changing tyres at all.
The compulsory four-tyre change will not be in effect for the other six rounds, including the Fuji 500km on 4 May, where it is likely that teams will double-stint at least one set of tyres.