The RACER Mailbag, February 8

The RACER Mailbag, February 8

Insights & Analysis

The RACER Mailbag, February 8

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Welcome to the RACER Mailbag. Questions for any of RACER’s writers can be sent to Due to the high volume of questions received, we can’t guarantee that every letter will be published, but we’ll answer as many as we can. Published questions may be edited for length and clarity. Questions received after 3pm ET each Monday will appear the following week.

Q: The Maximum Stint Energy for the Daytona 24 was 920 megajoules. I get that. It is measured by sensors on the driveshafts that detect how many megajoules (how much force) is applied to the tires by the drivetrain. Have I got that right? So, the maximum amount of force that can be applied to the rear tires of any GTP car during a stint at Daytona would be 920 megajoules.

Here’s the question: If all the cars weigh the same, and they all fit in the same aerodynamic envelop yielding the same drag (roughly) and downforce, how does Acura cover more miles using the same amount of force applied to the tires? The only thing I can think of is that the chassis dynamics of the ARX-06 allow it to run with less downforce and drag than its competitors, resulting in going farther on the same number of megajoules.

What are your thoughts?

Ed Joras

MARSHALL PRUETT: Yes, the torque sensors only record acceleration and apply that in the count up to the 920MJ stint limit. The Acura has been described for many months among its rivals as the fastest GTP car, and if we look at the basics of the situation, the ARX-06 drivers are able to make more speed on an average lap without having to rely on the throttle as much as their rivals.

Another factor to consider, which was raised by one of the best non-Acura drivers, was how Acura isn’t going to Le Mans this year. That driver — a Le Mans veteran, for what it’s worth — suggested the Acuras were likely racing at Daytona with more freedom than those brands headed to Le Mans where the ACO/WEC were looking hard at all data coming out of Daytona as a first opportunity to consider at how it will apply Balance of Performance restrictions. I’ll leave it up to you to decide whether Cadillac and Porsche held their performance cards — be it lap time or Maximum Stint Energy capabilities — closer to their chests than the brand that dominated the Rolex 24.

Q: How many is too many in driver lineups for the longer IMSA races? I well remember the days of two per car (Rodriguez/Kinnunen, Siffert/Redman, etc.) even for the 24-hour races. For me, three diluted the honor, though there were surely performance gains using fresher drivers. But four per car is overkill, which diminishes the awe in which I held the skills of “endurance” races. How do the drivers feel being one of four on a podium?

A. Jenkins, Brockville, Ontario

MP: This is an entirely made-up thing, a non-issue. Sports car rivers are hired (or pay) to try and win races in an ensemble cast, not to prove their toughness by doing it with the fewest drivers over 12 or 24 hours. And while the dangers were drastically higher in the Porsche 917 days, you won’t find a single legend like a Redman or similar who says they drove those monsters at 100 percent for an entire endurance event. Had they, three or four drivers would have been required. With modern sports car pros working in the maximum-attack model that’s been the norm for quite a while, you need three or four drivers to bear the physical load that comes with it.

How do the drivers feel about being one of four on the podium? Pretty good, as far as we can tell. Jake Galstad/Motorsport Images

Q: How much does it cost an OEM to have a GTP program, and how does that stack up to the amount Honda and Chevy spend a year in IndyCar? Is it dramatically cheaper to be in GTP/LMDh?

IndyCar seems to have the bigger audience but it struggles to find manufactures, while IMSA launched GTP with four unique manufacturers and will have a fifth next year. Is it all down to budgets, or is there more to it than money spent/ROI?

Thomas, Orlando, FL

MP: There’s really no such thing as a “GTP budget” since each manufacturer decides how much they want to spend, so it’s hard to do a straight financial comparison between the two. If I were to go off of operating costs per car, I’ve heard numbers in the $10-15 million range for a season, but that’s just the number to do all 11 races. Costs to design and build each GTP model, create all of the spares for multiple cars, all of the wind tunnel and simulator testing, track testing, staffing costs on the manufacturer’s side, and so on, would add a multiplier of 2X o 3X, easily, during Year 1. I heard one team had a $22 million operating budget in 2022 with two DPis, so I’d bet that $10 million could be low.

Same with IndyCar; Chevy and Honda don’t tell us how much they spend per year on supporting their teams, buying advertising, sponsoring IndyCar races, etc., so other than knowing it’s in the tens of millions, there are no specifics to offer.

It’s far easier to sell an auto company’s board of directors on a high-profile hybrid GTP program because of its greater technological relevance and closer looks to what they sell. With IndyCar, it’s more of a passion play that also involves legacy. Chevy joined IndyCar in the 1980s and Honda did the same in the early 1990s, both during the CART era, continued in the 2000s in the IRL/IndyCar era, and with the advent of the new-era cars and engine formula that debuted in 2012, the two were back at it and have never left. There’s real history for both with open-wheel racing and they feel an ongoing need to be here, which is amazing.

But for an auto company that doesn’t have decades of history and provenance in IndyCar, and has the option of doing a hybrid GTP car that can be styled to look vaguely similar to its road cars, or doing an IndyCar engine that’s hybrid but sits tucked away in the engine bay in a car that looks identical to the Chevys and Hondas, that’s a much harder sell to the board of directors. Throw in the fact that the GTPs are brand-new and doing an IndyCar engine would come with using the oldest open-wheel chassis in a modern racing series, and you can see why manufacturers are flocking to IMSA instead of IndyCar.