New and old cross over at Sebring in latest IR28 IndyCar test
IndyCar’s all-new Dallara IR28 returned to road-and-street course specification for a two-day test at the punishing Sebring International Raceway this week.
The car, set to debut in 2028, had previously run on the smoothness of both the Indianapolis Motor Speedway (IMS) road course and oval in August and September. For this week’s third test, the bumpiness of Sebring offered an essential opportunity to stress-test the IR28, giving the best gauge yet of the strength and durability of its components at this early stage.
As was the case in the previous two test outings, Chip Ganassi Racing’s newly-crowned five-time champion Álex Palou and Ed Carpenter Racing’s eight-time race winner Alexander Rossi were the selected drivers, running one day each in the sole chassis.
Palou took the wheel on Monday and completed 43 laps on Sebring’s outer loop, before his day was ended prematurely with a reported fuel-system issue. Once again, this latest test did not yet feature the 2028-specification 2.4-litre twin-turbocharged internal combustion engine - instead an Ilmor-badged mule designed for the scrapped 2022 engine regulations.
“We’re trying to test it as tough as we can,” Palou said. “It’s a bumpy course. Before we produce all the new cars, we want to make sure it passes this stress test and that it’s good to go for racing. We’re trying to get miles and miles, see what breaks so we can fix it.”
On Tuesday, with gremlins amended, attention turned to long running with Rossi in the car, moving away from testing purely of system functionality and towards a greater emphasis on how the package behaves over an extended period on track. The 2016 Indianapolis 500 winner ultimately completed a substantial 134 laps across the second day.
“The messaging we get is: ‘Run the car as if it’s your race car. From there, we’ll see what issues, problems, surprises come out of that,’” Rossi said. “I think all the test list items were really accomplished in the first two tests, making sure things worked as you would expect.
“This test is more of a practical application of: ‘Does it perform over a two-day test as the current car does? Does it do what it is expected to? What little things could come out of that that we need to address before the series produces a bunch of these?’”
Given its harshness and mixture of asphalt and concrete surfaces, Sebring is the test venue closest to replicating the rigours of a street course, meaning the IR28 is a shorter-oval test away from having been somewhat evaluated for each of IndyCar’s core track types.
The former Floridian airfield was also an ideal location to assess the IR28 in its formative stages given IndyCar frequents the track as a test setting, meaning there is no shortage in data from the current-generation Dallara DW12 chassis to compare with the new car.
The intention of the test was essentially to try and expose any weaknesses, but for the drivers, it equally outlined some of the IR28’s most redeeming features.
“It’s a new car for me at Sebring,” Rossi said. “Coming back here and being part of the next generation of IndyCar’s future is a huge honour. It’s an exciting time in this sport. This car, in so many ways, is a pretty big upgrade from what we have.
“What’s good about [Sebring] is it’s the poorest-quality surface you can have in a permanent road course. It mimics a street course, kind of. Because it’s a permanent road course, it gets used a lot so it’s a higher grip level than a street course. [But] in terms of bumps, pavement changes, difficult changes in the asphalt, that’s why everyone comes and tests here.”
For this latest test, feedback offered by the drivers after the IMS outings - in coordination with Dallara and IndyCar officials - had already been acted on. Palou noted that driver comfort has already improved, particularly in terms of cooling, with the IR28 featuring more integrated cooling ducts amid the aeroscreen no longer being retrofitted to the car.
“It’s been so much better, the cooling, since we started a couple months ago,” said Palou, who also noted an improvement in the braking. “Huge step - and that’s something we’ve been asking for a long time on our current car. We have a very big [duct] right in front of us [on the IR-28] that makes the air go from down to up and makes the airflow so much better.”
After his own return to the cockpit, Rossi concurred about improvements in cooling.
“First of all, visually, it’s an incredible race car to look at. It generates more grip in high-speed corners. It’s a very nice car to drive. It’s well-built and incredibly well-engineered,” said the Californian. “Cooling-wise, we made a pretty big step in this test, in particular. It’s night-and-day different in terms of comfort and drivability in the cockpit.”
The test also provided the novelty of the existing DW12 chassis running on-track with the IR28, as Andretti Global’s Kyle Kirkwood and Team Penske’s Scott McLaughlin conducted a Firestone tyre test for 2027 and beyond, alongside Palou’s new-car running on Monday.
In a limited amount of time on the circuit together, Palou ran behind and in the wake of the DW12 and also completed what was the first ‘overtake’ made with the IR28.
“It wasn’t planned,” said the Spaniard. “We went out and I saw Kirkwood was doing the tyre test. We spoke during lunch that at some point we would go together. We wanted to see how this car does in traffic. It was cool. We were playing a little bit.”
There remain over 16 months until the IR28 will debut in competition. But as Palou notes, with over four months until the DW12’s final campaign commences in 2027, this “gives us so much time to work on the car, to make sure it’s good” before its 2028 debut.
“There are more things that are scheduled to come as time comes that will allow this car to race and perform even better,” Rossi added, “that will only put on a better show for the fans, which is the No.1 priority for all of us.”
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