IMSA: Balance of Power Adjustment games leave Corvettes out to lunch for Rolex 24 (2nd Update)

Even though they are slow already due to Draconian measures, IMSA officials have given the two Corvette C8.R entries of Corvette Racing additional ballast weight ahead of this Saturday’s running of the Rolex 24 at Daytona.

As per a pre-event Balance of Performance (BoP) table published Tuesday, the two Corvette C8.R entries have received a 15 kilogram (33 pounds) weight increase compared to the specification they ran in during last weekend’s Roar Before the 24 test.

The team was previously granted a BoP break after it languished at the bottom of the GTD timesheets for the entirety of the Roar Before the 24, receiving a 1.5mm larger air restrictor and a three-liter fuel capacity increase. IMSA seems to believe these changes may have given the two Corvettes a pace advantage over the competition, however, hence the additional ballast.

Speaking to media following the Roar Before the 24 test, Corvette Racing driver Tommy Milner said the team was “not thrilled,” with their overall pace. While IMSA’s BoP adjustments brought the team closer to their rivals, the lack of pace can also be attributed to the team’s unfamiliarity with the new GTD-spec Corvette C8.R, which is heavier than the previous GTLM spec car, rides on different spec Michelin tires and utilizes ABS, among other changes.

January 26, 2022 

Let’s review the way IMSA (God) neutered the GTD Pro Corvettes, ensuring they cannot win the Rolex 24:

  1. The mass of the Corvette C8.R is increased by 65 kilograms (143 lbs.) relative to Daytona 2021. To accommodate the ballast box required by the GT3/GTD regulations to hold the extra weight, the Corvette Racing team had to reconfigure the entire passenger side floor compartment. This required the move of the air conditioning unit, fire bottle, battery box and other electronics. This was no small feat with integration requiring significant effort by the Corvette Racing engineering team.
  2. The 2022 Corvette GTD entry is running on customer Michelin tires, which are required for the category. This is a change from GTLM where the C8.R ran on confidential tires – ones that were specifically designed for Corvette Racing.
  3. The power output of the C8.R’s flat-plane V8 is significantly reduced under GTD rules. The difference between the size of this year’s Daytona air restrictor and 2021 is nearly 1.7 mm.
  4. Related to that, the GTD PRO Corvette is running with a higher angle of attack on the rear wing than previous years. This creates a greater level of drag on the race car and significantly reduces top speed.
  5. The addition of ABS is required under GT3/GTD rules. As many observers are aware, Corvette Racing tested this in competition for the first time last year at Belle Isle in the GTLM Corvette. The system continued to be improved throughout testing late last year and early this season both virtually and in the real world.
  6. The differential of the Corvette C8.R must now comply with GT3/GTD regulations. A limited slip differential configuration is permitted with a single homologated set of ramps. This required removal of some tuning options previously available on the GTLM Corvette.
  7. Unlike other GTD teams, the C8.Rs are required to run with torque axle sensors. These directly measure the output of the Corvette engine and the data is used by IMSA for the BOP process. Yet, none of the other makes have to run them, underscoring what IMSA is doing to ensure the Corvettes are not fast enough to win and repeat last year’s 1-2 finish.
Corvette C8.R No. 4 driven by Tommy Milner, Nick Tandy, and Marco Sorensen (Richard Prince/Chevrolet Photo).

January 23, 2022 

Corvette Racing finished up its first three days of official testing and competition in the new GTD (GT Daytona) PRO class of the IMSA WeatherTech SportsCar Championship on Sunday with work to do ahead of the upcoming Rolex 24 At Daytona.

The team finished eighth and ninth in class and 14th and 18th among GTD cars following a 100-minute qualifying race to set the grid for the Rolex 24 on Jan. 29-30. Sunday’s race was the first for the evolved Mobil 1/SiriusXM Chevrolet Corvette C8.R, which ran for all three days in GTD spec for the first time in a full-field setting. The results show the uphill battle facing last year’s GT Le Mans (GTLM) race-winning program. Antonio Garcia and Jordan Taylor – last year’s GTLM champions and Rolex 24 winners with Nicky Catsburg – in the mid-engine No. 3 Corvette C8.R led the team’s efforts but finished a lap behind the class-winning Lamborghini.

#4: Corvette Racing, Corvette C8.R GTD, GTD PRO: Tommy Milner, Nick Tandy, Marco Sorensen

The C8.R has undergone a number of changes from its two-year GTLM campaign to bring it in line with the existing GTD cars. Corvette Racing is running with more weight, less power, a higher level of drag, customer Michelin tires and an ABS system for 2022 compared to 2021. Even with a mid-week Balance of Performance adjustment by the sanctioning body in an attempt for more evenly balanced competition, the Corvettes still faced a significant performance deficit in Saturday’s qualifying and Sunday’s race.

Antonio Garcia said, “Knowing how little testing we did before the Roar, we used this race as a big test for tires. There are a lot of different things with the tire regulations where you have to run a certain pressure, and we learned a lot about that. It’s the first experience we’ve had with this. I was driving and learning how to maximize the tire performance. Even if we didn’t have the overall pace to be farther up, I think we can a lot from here for the race. Even if it’s only learning how to run a double-stint, it’s better than nothing. Almost all the other GTD teams have been running this tire on their car for a long time so there is a lot of catching up we need to do on this little thing. Let’s see if we can come back stronger in a few days so we can be where we need to be.”

Garcia’s teammate in the #3 Corvette said, “The race was a qualifying race so you can’t really win too much in that event. It’s pretty much just about setting us up for the Rolex. For us, we know the car we have now. Throughout the Roar, we made some developments and gathered more data to hopefully set us up well for next week. That’s the one that counts. We still have some more work to do in order to understand the ABS, the new tire and everything. The guys will have a busy week ahead but I know we’ll come back strong next week. Understanding the racecraft of this category was important. We’re now mixed into a new class with GTD and Am drivers as well. Understanding how they race and how we will interact is useful. It’s a lot harder to get by them now that we have the same BoP, so it will make for a long and interesting 24 hours. It will make staying out of trouble that much more important than years past.”