IMSA: Breaking Down The Pre-Sebring Balance Of Performance Tweaks

Photo Credit: IMSA

Disclaimer: Views and opinions are those of the writer of this article and not necessarily held by or its other staff members.

After a wild and highly competitive Rolex 24 at Daytona last month, in which several cars were in contention for overall and class honors in each of the IMSA WeatherTech SportsCar Championship’s four divisions, the series competition committee issued this past week the first of an expected pair of Balance of Performance adjustments across all of the confrontational classes. This of course rules out Prototype Challenge, where all entrants utilize the same ORECA FLM09 chassis and Chevrolet V-8 engine, an engine which could provide more power at Sebring, if paddock talk is accurate.

Looking ahead to the Mobil 1 12 Hours of Sebring next month,  some of the tweaks are understandable, especially involving the teams and cars who either won their division or were soundly outclassed on pace. However, some of the changes in the eyes of yours truly have left me a bit stumped. Some that were competitive at Daytona International Speedway were given breaks that based on both the timing chart and the eye test may not have been warranted. Well boys and girls, with that primer on the table let us have a glance at what tinkering is now on the books shall we?

In Prototype, following a strong victory in the Rolex 24 at Daytona by FIA World Endurance Championship regulars Extreme Speed Motorsports, the Ligier-Honda coupes in both their hands and for Michael Shank Racing will suffer a reduction in the maximum turbo boost that the 3.5 liter V-6 Honda turbo can generate, however the car itself suffers neither a weight addition nor was given a drop in mass at this point. ESM’s biggest threat to its overall victory at the Rolex 24, the quartet of Chevrolet Corvette DPs were aided the most for Sebring, as their V-8 GM power plant will feature a larger air restrictor by 0.3 millimeters. The car’s minimum weight was also reduced by 10 kilograms prior to IMSA’s two-day test at Sebring International Raceway this week.

The adjustments to me are a bit of an overreaction by IMSA in this case. While ESM did win at Daytona, MSR blew up their Honda engine prior to the halfway point, yet really did not show a clear speed edge over the Daytona Prototypes from both Corvette and Ford, the latter of which will not return at Sebring. In fact, during the final two hours of the race last month, the Wayne Taylor Racing Corvette DP was faster than the ESM Ligier-Honda, up until ESM’s star driver Pipo Derani took the wheel of the No. 2 Tequila Patron-backed Ligier to the finish. So based on that, the chasm of difference between the two makes that Action Express Racing’s Christian Fittipaldi complained about on IMSA Radio during the race, I do not think is as big as he is claiming.

In addition to the changes for the Ligier and Corvette, the feel good story of the first four hours, the Dr. Don Panoz-entered DeltaWing DWC13 coupe was also hit with handicaps. The smallest and lightest car in the Prototype division, will run 10 kgs heavier at Sebring, plus its Elan turbo engine will suffer a boost decrease similar to what will be done to the Honda, except it will administered across the board, rather than solely at max power like with the Honda. The other P2 surprise, the Mazda Motorsports Lola coupe was given further assistance for Sebring and like the Corvette DP will run 10 kgs lighter.

While the weight and boost cut could hurt Katherine Legge and DeltaWing in qualifying, I can still see scenarios where the DeltaWing could vault itself into the overall lead and victory conversation, as it did at Daytona on two occurrences, prior to Andy Meyrick’s unfortunate collision with the stopped Starworks Motorsport PC entry. If Mazda can extend its reliability beyond what was achieved at Daytona, the drop in weight might be all that is required to make them a threat near the front in the early hours next month.

The question of course, is how the new kids on the block; DragonSpeed’s ORECA 05 coupe with Nissan V-8 power will be treated by IMSA once testing numbers are posted this week. Like the Ligier coupe, this entry which crushed the competition last year in the LMP-2 division at the 24 Hours of Le Mans, could catch the IMSA mainstays off guard in its sole prep race prior to joining the European Le Mans Series circuit this spring.

In addition to the extra weight on two of the LMP-2 based cars, all of the entrants of this Prototype form will switch to the high down force aerodynamic kit for Sebring, as opposed to the lower drag package utilized at Daytona. While not a major concern, the switch could give the Daytona Prototypes the edge on the Ullman Straight run toward the final turn at Sebring International Raceway; the Sunset Bend hairpin.

I still think the chances of a LMP-2 matching ESM’s win at Daytona are still good, but the reigning Sebring winners Action Express Racing, along with Wayne Taylor Racing and Racing from the Corvette DP camp could be much more potent here, if the race outcome’s biggest factor is maximum horsepower output.

Shifting gears to the always competitive GT Le Mans division, Corvette Racing was as expected tagged following its 1-2 finish at Daytona, culminating in a near dead-heat conclusion at the finish line. The pair of millennium yellow C7.Rs will be 10 kilograms heavier at Sebring and will feature a 0.4 millimeter cut in the size of the air opening to its supercharged V-8 engine. The Pratt and Miller-built racers completed a private test with the adjustments added this past week at Sebring and will not be at the open test this week.

While the changes for the “Fehan Flyers” were expected, the adjustments for the other manufacturers were a little odd. Despite struggling in terms of both outright pace and reliability at Daytona, Chip Ganassi Racing’s Ford GTs will also pack on an extra 10 kilograms on their minimum weight, plus its twin-turbo V-6 Ford EcoBoost will suffer a drop in boost power.

In comparison, the German manufacturers in the division were aided a bit ahead of the 12 Hours of Sebring. After placing best of the rest behind Corvette at Daytona, Porsche North America’s pair of 911 RSRs will compete minus 10 kilograms in weight, while BMW Team Rahal’s M6 GTLM will feature an increase in boost power for its twin-turbo V-8. For now, there are no Balance of Performance changes mentioned for the Ferrari 488s run by Risi Competizione and Scuderia Corsa.

The penalties on the Corvette C7.R were expected as the Doug Fehan-led challengers had the class field covered in terms of both pace and durability last month. However, the reduction in weight on the Porsche is interesting since only an incidental clip by Oliver Gavin on Earl Bamber cost the 911 RSR the top spot during the final hour. As was mentioned above in Prototype, the perceived pace advantage was not as big as was advertised by those who failed to reach the winner’s circle, especially in the case of the Rahal BMWs, who were the fastest of the GTLM fleet during the Roar Before the Rolex 24 open test and during the final practice session prior to race weekend, the only dry running before the Rolex 24 during race week. While a return to the dominant form shown by Porsche North America in the second half of the 2015 IMSA season is possible, Corvette and the other marques should stay within range come race weekend next month at the former air force base turned bumpy and challenging road race circuit.

Finally in GT Daytona, two of the three podium placers were handicapped this past week. The Porsche 991 GT3-R, which finished second in the Rolex 24 via Black Swan Racing, will race with the customary 10 kilogram increase in weight, while Ben Keating’s Dodge Viper GT3-R will have 15 kgs added. However at least with the first set of BoP swaps, the Audi R8 LMS which won the race through the efforts of Magnus Racing, will enter the Sebring tests for now unchanged in terms of its technical makeup. Only the older version of the R8, run by Tracy Krohn and Flying Lizard Motorsports’ allied effort was affected this week and like the Porsche 991 will run 10 kgs extra in weight.

After suffering from both pace and durability issues at Daytona, Turner Motorsport’s BMW M6, as with their GTLM big brother will feature an increase in turbo boost output, while the Keating Viper will feature a larger air opening for its eight-liter, V-10 engine. TRG’s Aston Martin V12 Vantage will have their air restrictor size reduced.

Sebring will see a mix of both the older Ferrari 458 GT3, along with the brand new Ferrari 488 GT3. AF Corse’s Spirit of Race will call upon the old mount, while Scuderia Corsa acquired their new 488 earlier this month and will debut it on track for the first time at the Sebring open test this week. Only the 458 was dealt with by IMSA in this set of BoP adjustments, as the car will run with 10 kgs removed from their efforts at Daytona.

The biggest question though is what will IMSA do in terms of the brutally impressive debut at Daytona by the Lamborghini Huracan GT3. The series impounded the car’s powerful five liter, V-10 engine after the Rolex 24 and have been running tests on it at the NASCAR Research and Development Tech Center in Charlotte, North Carolina. Weight or power cuts for the challenger in advance of Sebring should be revealed in the second set of adjustments after the open test this week.

Although the Lambo’s performance will remain a mystery at this time, none of the changes appear likely to greatly influence the potential outcome at Sebring in comparison to Daytona, with maybe a more competitive outing from Turner Motorsport being in the cards. Once the second set of pre-Sebring changes are lay out, the picture will be easier to evaluate.

Stay tuned to, for more news and commentary on the world of sports car racing by Matt Embury.




  1. Hi OPR, Like your Web site, found it while looking for articles regards IMSA BoP for Sebring. Say, just a heads up—-C7.Rs are not supercharged as described in your article, IMSA: Breaking Down The Pre-Sebring Balance Of Performance Tweaks, but are naturally aspirated 5.5 Liter Small Blocks based on the LS7 engine.
    On an other note; I don’t subscribe to any social media, not that I’m technically challenged, just a personal choice. I was looking for a way to digitally subscribe to OPR. Did I miss that? Thanks, Mike Waal, Member: First State Corvette Club [club reporter for all Corvette racing activities IMSA, T/A, SVRA], NCM

    • Currently, outside of the social media options, we do not have an option to subscribe to the website. But thank you for stopping by and commenting.

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