IMSA Prototype Hybrid Era Begins this Week

Cadillac has three entries from Whelen Engineering and Chip Ganassi Racing - photo courtesy Cadillac
Cadillac has three entries from Whelen Engineering and Chip Ganassi Racing – photo courtesy Cadillac

IMSA’s new season begins this coming weekend with the Roar Before the Rolex 24, held at Daytona International Speedway. This three-day weekend preface to the 61st Rolex 24 at Daytona, the midwinter 24-hour race conducted mostly in darkness, sets the field for that race with IMSA’s class-by-class qualifying sessions, after a few rounds of official practice to get the 61-car field acclimated with new race cars, with the track (in most cases re-acclimated), with one another and with the current conditions on the 3.56-mile road/oval circuit. 

There was a December two-day test for the incoming prototype class, the LMDh cars that were introduced prior to the 2020 running of the Rolex 24, cars that IMSA has elected to call GTP. The rationale for giving them that name is that it evokes cars that were manufacturer-based back in the 1980s to the 1990s, prototypes that were very popular with both competitors and with fans. The new GTP cars are also manufacturer-based, with Acura using an ORECA chassis, BMW and Cadillac turning to Dallara and Porsche equipped with Multimatic tubs. All these cars are equipped with bodies that look similar to what each manufacturer – Acura, BMW, Cadillac and Porsche – produce for the street.

With new engines that feature energy recovery systems, just as the World Endurance Championship (WEC) Hypercars do, the 2023 IMSA WeatherTech SportsCar Championship GTP class will be very different from last year’s engine packages. This regulation change to hybridization allows IMSA GTPs to race at the summer 24 Hours of Le Mans next June. The system consists of a common gearbox casing and internals, produced by Xtrac, with a Bosch motor generator unit (MGU) and control electronics. The regenerated energy is stored in a battery pack developed by Williams Advanced Engineeering.

While there are 13 Hypercars on this season’s WEC championship entry, there are nine GTPs entered for the 61st Rolex 24 at Daytona, with a single entry unable to make the call at this time, JDC Racing, due to parts shortages and challenges facing them as the first Porsche 963 customer team, while Porsche Penske Motorsports campaigns two 963s as factory team. Cadillac Racing will have three cars, two from Chip Ganassi’s Indianapolis squad and a third from Whelen Engineeering Racing for its V-LMDh prototypes. Acura’s ARX-06 is campaigned by last year’s race winners, Meyer Shank Racing and by Wayne Taylor Racing with Andretti Autosport. Rahal Letterman Lanigan’s BMW squad moves to the GTP level from GTD PRO with a pair of BMW M Hybrid V8 cars. And all of them bear familial resemblance the manufacturer who are racing in this series. And in the WEC.

The engines are different, as well, subscribing to efforts each manufacturer has taken in the past for its sports prototypes. All of them using the hybrid technology, of course, but in different ways. Acura has developed a twin turbo V-6 engine (it races a twin-turbo V-6 in INDYCAR competition); both BMW and Porsche opted for a turbocharged V-8 engine; Cadillac is using a 5.5-liter, naturally aspired V-8 power mill. It will be interesting to see which engine/hybrid combination works best on the long Daytona racetrack, once true competition begins.

At the first test, the consensus was that the cars were quick and fast, but it wasn’t certain they’d be as durable as necessary for 24 hours of pounding round. The 2022 edition of this race was cold; the 2020 version was exceptionally wet. Weather situations are something no one can control, but teams will be prepared to face all and any of them. 


Acura’s teams are both winners of this race: Wayne Taylor Racing with Andretti Autosport and Meyer Shank Racing – photo courtesy WTR

One attraction for the four manufacturers currently entered in get GTP class is open software. “It attracts the next generation of engineers,” noted David Salters, president of Honda Performance Development (HPD), which produces the power units for Acura. Salters, who worked in Formula One with Ferrari before coming to the US and HPD, can use that experience moving forward in the IMSA arena. He mused, as the season gets closer, that the biggest challenge at this time is to “keep parts and pieces on the shelf. We are working with our teams and trying to be sensible as we make a fast racecar: from A to B… we hope to have a complete racecar after 24 hours!”

That intent is always what an engineer or team manager is looking for in a race like the Rolex 24 at Daytona. Salters’ cohort at Cadillac, Rory Harvey aims to keep parts on the shelf and solve any issues that could crop up that might hinder success. Cadillac has been racing DPi in the WeatherTech series and has championships, along with race wins, to show for it. Cadillac brought its engine program in-house after using ECR Engines’ power mills for its previous-model prototypes. 

Porsche returns to IMSA with Penske – the same team it ran with in the ALMS series – photo courtesy Porsche

Porsche first used hybrid power in a GT3 car at Petit Le Mans, the traditional season-closing race for IMSA (and for ALMS before it joined with the Grand-Am Series in IMSA). That car had Porsche’s traditional boxer engine with hybridization. Thomas Laudenbach, who has charge of Porsche’s engine program has stated the company would be putting “all of our experience into this racecar.” The Balance of Performance (BOP) that IMSA and WEC use to keep parity “is more restrictive, but we’re not negative about it. We want to control costs and this is a new situation we’ve never had before.”

BMW’s Andreas Roos is also concerned about the people on his team and having the best program available for them. He’s been asked, copious times, about the possibility of placing new GT driver Valentino Rossi, the former MotoGP champion, into one of the GTP cars campaigned by Rahal Letterman Lanigan Racing (RLLR). The answer has been, again regularly, that Rossi has to show his capabilities in a GT car before he’s eligible for placement in a GTP prototype and that will have to come with time. Unwillingness to talk about the performance of his cars without seeing them in practice, qualifying and competing in the 24-hour race might be the smartest thing Roos has done.

BMW’s Rahal letterman Lanigan Racing GTP car debuted in Los Angeles – photo courtesy BMW

And so, with four marques prepping to be kings of this 24-hour mountain, it remains to be seen which will be quick out of the box and which, if any, can go the distance of 24 hours. It bears reminding that, 20 years ago, it was a Porsche GT car that won the overall Rolex 24 at Daytona. The Racer’s Group (TRG) and its owner Kevin Buckler are celebrating that victory – albeit off-track – in the Daytona International Speedway infield during this upcoming race weekend. Perhaps they’re wanting to see if that kind of lightning strikes twice?

About Anne Proffit 1246 Articles
Anne Proffit traces her love of racing - in particular drag racing - to her childhood days in Philadelphia, where Atco Dragway, Englishtown and Maple Grove Raceway were destinations just made for her. As a diversion, she was the first editor of IMSA’s Arrow newsletter, and now writes about and photographs sports cars, Indy cars, Formula 1, MotoGP, NASCAR, Formula Drift, Red Bull Global Rallycross - in addition to her first love of NHRA drag racing. A specialty is a particular admiration for the people that build and tune drag racing engines.

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