IndyCar will replace its engine formula for 2023 with twin-turbo 2.4-liter V6 engines augmented by a hybrid unit. So, Meyer Shank Racing-Honda and Arrow McLaren SP-Chevrolet raced for Firestone at Indianapolis Motor Speedway on Friday, so the series tire partner can assess the possible effect of the increased weight, revised distribution weight and increased power.
However, Firestone also took the opportunity to do a more “internal” audit, as Cara Adams, director of racing tire engineering and production at Bridgestone Americas, explained to Motorsport.com.
“The main objectives of the test were (1) to test tires on cars that simulate the increase in power, increase in weight and the modified weight distribution that we will see in 2023, and then (2) to prove the tires from our new factory. It was the first time that we had tires from our new factory on the track so we wanted to make sure there were no differences, and that if there were differences, they were minimal.
“This new facility is still in Akron, less than a mile south on Main St. of our current facility, and almost directly across from our Bridgestone Americas Technical Center. But that’s the difference to be in a building that is over 110 years old and a building that was built specifically for this new experimental production.
“So in testing the cars came off the trucks like they would have raced in the Indy this year. The cars were a little slower, going at 215, 216 early in the day, but we were able to replicate everything. we needed to see. We used a set of current Indy tires as the test tires and then we did a direct comparison to those at our new facility. And that part of the test went pretty well.
“Then around 11 or 11:30, we went down for about 90 minutes to give the teams time to add weight to the car. We worked with Dallara and IndyCar to create a bell that could take on more weight and replicate as closely as possible what we think we will see in 2023. The weight distribution is about 1% rearward and about 120 pounds of weight. load was added.
“And obviously the new engine formula will see more horsepower as well, so IndyCar asked Honda and Chevrolet to run their engines to replicate that horsepower increase. [60hp, just under 1.5-bar from the BorgWarner turbos, according to Bill Pappas, IndyCar’s VP of competition]. Then we tried this year’s tires – the same ones we’ll be using in 2022 – to re-tune the control, and then we used two new compounds on the right side, two new compounds on the left side, to get data. from these. Once we get a little more precise idea of the actual increase in weight and power and finalize the weight distribution, we’ll go back and test some more, but this test definitely got us in. the right way when it comes to compounds.
“There was a little difference, because we also adjusted the tires to help the cars in terms of overtaking, giving a little more grip. But there was not much difference between the behavior of the current tires with the cars in the current configuration and the behavior of the experimental tires with the cars in the 2023 configuration. We tried to make sure that we collected data on cars running in clean air, then running together, so the second car in a row was in dirty air. “
Adams admitted that, as always, it was difficult to predict tire behavior based on test data acquired from a dense and airy October day in what could be a 90-degree day for qualifying and / or the race next May.
“As you know, we could have a month of May in the 60s or above 100 degrees! ” she said. “So we have to plan for a compound that can work in all conditions. The performance and behavior of cars can change a lot with the amount of air density, so we have to design around that, hit a median, and make sure our compound and structure covers a wide window.
“And so we take note of every change in wing angle that the teams make and, more importantly, we look at all the data that comes out of the car. So when the event is over, we will have a great set of data. of each car, so we know all the fender angles, suspension settings, roll bar settings, so that we can calculate the loads on the tires. Then we will compare that to the historical race data and to previous tests, then we extrapolate from there. ”
Having a 21-time starter and four-time race winner as one of the testers was a big help, Adams said.
“We did a little media thing with Helio before the 500 this year, and it was decided he was going to interview him,” she said. During this interview, he commented: ‘You don’t test much with me anymore. What do I have to do? How can I test your tires? ‘ I said to him: ‘Helio, all you have to do is win the 500 again. He said, ‘Really?’ I said ‘Really! Then you can test the tires for us. Well he won the 500, so at Gateway when we told the teams who we wanted to test for us, I said, “Helio, remember the deal we made…” Of course he was very happy to have this chance.
“The people we test with always give us a little different feedback, each one has a different style of communication. It was the first time we did tire tests with Pato and his feedback was really good. It’s nice to have that relative unfiltered newcomer perspective when someone who’s been on the show for years and years, they expect a certain thing and if not exactly what they expect changes their point of view.
“So the feedback from Pato and someone like Helio who has driven so many generations of cars on the Speedway and done so much testing for us in the past has given us a good experience and a good perspective. “
Next week, Josef Newgarden of the Penske-Chevrolet team and new Chip Ganassi Racing-Honda champion Alex Palou will test in Mid-Ohio with their chassis in spec 2023 simulated, i.e. with the new weight and the new weight distribution. Pappas confirmed to Motorsport.com that they will also see their turbos cranked up to just under 1.7 bar, to represent the base increase from 90 to 100 hp from the 2.4-liter engines in road specs and of road. Firestone will therefore once again have the opportunity to verify various tire specifications, including examples produced in its new factory.
“Obviously, the short oval and superspeedway tires require a lot more precision,” says Adams, “but we have the same discipline to build all of our tires, regardless of the type of site. We have to do this, because on a road / street course you can run in even greater temperature variations – 45 degrees F ambient to 100 degrees – so between that, with the increase in power, and the increase in hybrid power that drivers control, plus weight and what that does for load transfer when accelerating or braking… there’s a lot to look at.
“We feel fortunate to have great partners at Honda and Chevrolet and to be able to rely on their simulation capabilities to predict what the tire requirements will be. But there is still no substitute for track time.