IndyCar's IR28 completes first long runs as Rossi takes the wheel during Sebring test

Alexander Rossi took over from Alex Palou as test driver for IndyCar's 2028 chassis on Tuesday at Sebring International Raceway, and made up for the time lost on Monday when an engine issue cut the running short by 2.5 hours.

With Palou’s 43 laps on Monday and an unofficial best lap of 0m53.3s turned in the 2.4-liter twin-turbo V6 Ilmor-powered Dallara I28 to build upon, Rossi more than tripled the mileage on Tuesday with 134 tours of the Sebring short course and an unofficial best of 53.2s in the same hot and humid conditions that pushed above 85F.

After working through a few braking issues, Rossi was able to perform a number of longer runs on new Firestone tires, which was a first for the IR28 as all of its previous testing has centered on shorter runs. Beyond some damping changes that were sampled, Rossi closed the day by running with a new and stiffer set of brake calipers supplied by the Performance Friction Corporation and nearly matched his best lap of the day during the stint.

Mike O’Gara, IndyCar’s VP of Competition, Race Engineering, who oversees the IR28 testing program, shared his thoughts at the conclusion of the two-day run.

“It's a combination of durability testing, along with testing some more components on the car,” O’Gara told RACER. “There at the end, we had a bit of a thrash because there are a couple little things we're trying to get in. Engineers always ask for just one more run, so the track was generous enough to get us an extra 30 minutes, and we checked off a couple things that were question marks for us.

“Did some long runs for Firestone today. Really, the first time we've done long runs to see where the balance would go, and man, the lap times are super-consistent. Everything there looks really good. We tried a couple things for Firestone to get them some more data on not just next year's tire, but some stuff for ‘28. Broke a couple small brackets, and not even broke, but we see some wear on some areas that we know we're going to have to beef up a little bit, maybe trim a couple things back.

“Learned a little bit about the skids and how they wear, and make a couple improvements there. But overall, it just ran. It fired up, and it goes. And yeah, we had a little hiccup yesterday, but nothing major. Obviously, we got going again. I feel bad that Mr. Palou didn't get more laps than he did. He really enjoys driving this car, and we enjoy his company here and his value his feedback. So, shame he didn't get more miles in. But Alex Rossi today was an ironman in the car. I mean, he just sat in there all day, and it was hot. But the good news there is he's very complimentary of the ventilation in the car and the cooling.”

Rossi and the IR28 have a day off and get back to action on Thursday and Friday in Naples, Florida, where they’ll conduct straightline aerodynamic testing and verification on the two-mile runway.

Learn more about the day and hear from Rossi below.