One week after the green light of the 12h of Sebring, the IMSA SportsCar Championship has taken a step back, returning to the definition of the 2023-style Balance of Performance for the GTD PRO and GTD Classes.
The new system made its debut at the 24h of Daytona which involved data collection in collaboration with the manufacturers, who provided a series of information regarding the power and performance of the respective GT3 cars.
But the penalty inflicted on Ferrari and BMW at the end of the first race of the year made those directly involved think and especially discuss, which led to a sudden about-turn on the part of the top management of the American series, which has now returned to the system used during the last season.
#70 Inception Racing McLaren 720S GT3 EVO: Brendan Iribe, Frederik Schandorff, Ollie Millroy, Tom Gamble, #32 Korthoff/Preston Motorsports Mercedes AMG GT3: Mikael Grenier, Mike Skeen, Kenton Koch, Maximilian Götz
Photo by: Bob Meyer
“On Thursday we completed a technical working group with the manufacturers in which we discussed the process and performance objectives for Sebring”, explains Matt Kurdock, Technical Director of IMSA, speaking in a meeting with journalists to make the point of the situation.
“The manufacturers felt that continuing to work towards common performance objectives would be difficult, especially because there was no possibility to conduct a dedicated, IMSA-sanctioned test ahead of Sebring and collect data and information to check that everything was right. according to calculations and expectations”.
“At their request, IMSA took matters into its own hands for Sebring. Some of the 2023 data was combined with other data collected at the 24 Hours of Daytona, resulting in a BoP solution for Sebring that is basically a mix of these information sources available”.
“In this case we opted for a more traditional method of defining the BoP, but continuing with the greater transparency that IMSA has developed with the working group, providing a common table to discuss it collectively.”
“As regards the GTP Class, the BoP system is different from that of GTD PRO and GTD, and remains unchanged compared to last year. For the moment, no other official tests are planned during the season.”
#13 AWA Corvette C8.R GTD: Orey Fidani, Matthew Bell, Lars Kern, Alex Lynn
Photo by: Bob Meyer
Kurdock also added that for next year they are thinking of introducing the torque sensor which has already been adopted by the FIA WEC on the new LMGT3 cars, in order to have more accurate data collection and also working following that much publicized convergence between the series, for now achieved only with the LMDh.
“Some significant changes to the technical regulations for the GTD and GTD PRO classes are expected in 2025, with the introduction of torque sensors, similarly to what was done in LMGT3.”
“I think it's a wonderful opportunity to make sure the technology is integrated correctly with the IMSA electronics and with the car, combined with getting some sample data on the cars under controlled conditions.”
“We are still verifying the feasibility of this operation, it is an aspect we are working on with the GTD Manufacturers group at the moment in order to update the technical regulations with this equipment.”
“I think the experience we have had with this system in GTP is very positive, not only in terms of the ability to control power with a common methodology and measurement, but also in the implementation of elements such as virtual energy.” .
“In our opinion, this allows for better competitive equivalence between the different engine architectures and the possibility of obtaining a greater balance in giving up race pace to gain on stint length.”
“But these are details we are still working on. For our part there is a very open dialogue with the FIA and ACO and the two groups working on performance constantly exchange information on what they see in their respective championships.”
“I don't know at the moment if we will have the same supplier of this technology, certainly there would be many advantages in using the same or similar methods. We will probably have more information to share in a few months.”
Departure
Photo by: Jake Galstad / Motorsport Images
12h of Sebring: how the BoP changes
Having said that, let's see in detail how the parameters will be imposed on the GT3 cars of the 11 manufacturers present between GTD PRO and GTD at Sebring, pointing out that they all remain with the same engine rpm previously established and ground clearance at 50mm.
The biggest blow in terms of weight goes to the Porsche with +35 kg compared to Daytona and therefore on the track at 1360 in total, still seeing the average power increase by 19.2 kW and also the diameter of the restrictors to 39.5mm (+3.5), over to the tank which can now hold 100 liters (+3 l).
The heaviest cars, however, will be Mercedes and Ferrari, the ones that won in the first event of the season. The AMG will run on 1390 kg (+15), with the same 34.5mm restrictors and a slightly larger tank for 104 liters (+1).
The 296 GT3s instead receive 15 kg to reach a total of 1380, losing 9 kW of average power and increasing the tank by 1 liter, now at 105.
#1 Paul Miller Racing BMW M4 GT3: Bryan Sellers, Madison Snow, Neil Verhagen, Sheldon van der Linde
Photo by: Jake Galstad / Motorsport Images
15 kg in addition also go to Lamborghini, which will run on 1370 with a 51 mm restrictor (+1.0) and benefiting from a power increase of 6.5 kW, while the tank is increased to 113 liters (+4.0).
The Lexus also has the same weight as the Porsche, dropping by 10 kg, now fitting a double 39mm restrictor (-1.0) and losing 5.9 kW of average power, but also a couple of liters in the now 105 liter tank.
Continuing in order, the Corvette will run with 1345 kg (+10 now on board) and will have the same 50mm restrictor, but one liter less in the tank which therefore goes to 104 total.
The weight of the McLaren remains 1330 kg, which sees the average power increase by 4.6 kW, but the tank decreases by 110 liters (-3.0).
Even Aston Martin and Acura do not have different ballasts, being able to compete at 1325 and 1320 kg respectively. However, the Vantage GT3 EVO increases power by 6.9 kW and loses 3 liters in the 106 tank, while the NSX gains 5 kW and 1 liter, reaching 112 in total.
On the other hand, BMWs reach the same weight as Japanese-American cars with 10 kg of ballast added, losing 9.1 kW and 2 liters in the tank (now at 99, the least capacious of all).
Finally, the lightest of all will be the new Ford Mustang with its 1315 kg, receiving a 15 kg discount compared to the Daytona, but with an extra liter in the tank (110 l). The restrictors, however, remain 35 mm.
#34 Conquest Racing Ferrari 296 GT3: Manny Franco, Albert Costa Balboa, Alessandro Balzan, Cedric Sbirrazzuoli, #023 Triarsi Competizione Ferrari 296 GT3: Onofrio Triarsi, Charles Scardina, Riccardo Agostini, Alessio Rovera, #85 JDC/Miller MotorSports Porsche 963: Tijmen van der Helm, Richard Westbrook, Phil Hanson, Ben Keating
Photo by: Art Fleischmann
Among the LMDh prototypes of the GTP Class, the debut Lamborghini SC63 will begin its adventure with 14kg more on the minimum weight, therefore rising to 1044 kg, with combustion engine rpm set at 8200, maximum power of 513 kW and 908 MJ of energy at arrangement for stints.
Clearly all parameters that cannot be compared with what happens in the FIA WEC, where Hypercars are also on the track and the levels must inevitably be compared differently.
After the great suffering of Daytona, the Acura rightly sees itself taken off in weight, dropping to 1055 kg (-17 kg), maintaining 9512 rpm for the ICE, but also seeing maximum power (512 kW) and energy (910 MJ) drop.
The victory at the 24h in Florida brings to the Porsche a drop in power to 508 kW (-11 kW) and energy to 904 MJ (-13 MJ), but also by a couple of kg on the total weight which is now 1049 kg, remaining instead at 8158 rpm.
Once all the ballast has been removed from the BMW, by losing the additional kg it will be able to run on its basic minimum of 1030 kg. The M Hybrid V8s remain with ICE at 8000 rpm and will have 506 kW (-8 kW) of power and 898 MJ (-10 MJ) of energy.
A big blow goes to Cadillac instead, which if it didn't have any extra weight on the 'Rolex 24', here it gets 30 kg. As compensation, the V-Series.R receives a power increase of up to 520 kW (+10) and energy to 918 MJ (+16), with engine rpm still at 8800rpm.
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