RACER’S Marshall Pruett has spent the last year tracking developments with the IndyCar Series’ new chassis, engine, and the rest of what’s on the way for 2028, which we’re presenting in a multi-part feature. So far we’ve laid out the timeline for the rollout and explained what to expect from the new chassis and how the series arrived at the new engine formula. We’ve also taken an in-depth look at what that engine formula entails, how the series could bridge a gap year in engine suppliers, and options for getting the new engines built. This installment is the final in the series.
Welcome to the most interesting area to explore with the 2028 IndyCar.
Although answers are available for almost every aspect of the upcoming chassis and engine formula, hybridization is the last significant portion of the 2028 puzzle for IndyCar to solve.
“With the hybrid, we are currently looking at a 60-volt-or-less system, but substantially more on the energy storage,” Mark Sibla, IndyCar’s Sr. VP of competition and operations, told RACER. “Chevy and Honda should get a ton of credit for working hastily to put a program together with a hybrid that’s certainly effective, but also very robust. And that’s Version 1.
“Version 2 is, ‘OK, we’ve had a lot of learnings. Let’s keep the reliability. But boy, there’s some new technologies out there that maybe give us more energy storage and make this more impactful.’ We’re going through that process now. We’ve got to understand a little bit of where that ends.”
Version 1, which made its competition debut in July of 2024, was born out of necessity, with supercapacitors chosen as its energy storage system (ESS) due to the restrictive space available to fit an ERS battery in a Dallara DW12 chassis. As its design brief was formulated late in 2010, the DW12 was never meant to carry ERS units which, more than a decade later, complicated every aspect of the hybridization initiative when the series opted against building a new hybrid-specific car in favor of retrofitting the DW12 with a hybrid system.
For the upcoming IR28 chassis, ERS Version 2 will be packed into the same spot chosen for the DW12 – the tiny cavern hidden behind the internal combustion engine – within a structural bridge known as the bellhousing, where the motor generator unit (MGU) also lives.
The bellhousing covers the clutch and connects the transmission and rear suspension to the back of the engine, and in its original guise, the space above the clutch was used to house the single-turbo option Honda went with from 2012-2013 before IndyCar made twin turbos the spec from 2014 onward. Once the twin-turbo regulations were adopted, the former home for the single turbo sat empty until hybrids came online.
The series has gone to the industry using the same fact-finding process it followed with its first-generation hybrid, and has asked for proposals to be submitted by vendors who would supply its second-generation energy recovery system (ERS). Few restrictions have been placed on what the series will consider for adoption, but it will likely be an updated take on today’s IndyCar hybrid package.
“We’re looking at either something similar in its bellhousing size, or it could be perhaps a little smaller,” Sibla said. “So as we look at those energy storage solutions, this is the area that I feel is just continuing to evolve the fastest.
“You’re seeing technologies that, quite frankly, the actual capacitors we have now are just getting ready to be decommissioned as they move to a new capacitor, because each technology evolution just goes so quickly.”
In what the series is seeking, a steep rise in battery storage capacity to give drivers a longer duration of power deployment – upwards of 10 seconds per charge, which would double the five seconds on tap with Version 1 – is central to IndyCar’s ambition for multiplying Version 2’s storage many times over.
“Right now, two groups have moved themselves to the forefront on this project, and both have recommended similar solutions, slightly different, but similar, and both will reduce weight of the ESS, but also you’ll see more of that storage,” Sibla said.
“Now, to the question about why do we want more storage? I would say it’s twofold, but primarily, it is duration. When we sent out a request for proposals, we did have a duration target and asked if this is something that’s achievable or not. That’s why you put it as a target. And that certainly looks like it’s achievable, which would elongate the deployment.
“What we have to take a look at, and once we home in the specific opportunity between these two that we want to continue to pursue, it’ll be what is that balance between an increase in horsepower and duration you get because, when you go up in one, you in essence go down in the other.”
Technology has evolved since IndyCar’s first hybrid units appeared in 2024. Matt Fraver/Penske Entertainment
IndyCar also has a goal of doubling peak ERS power to 120hp.
“Now, because of the enhanced capabilities of these newer ESS, you could go up in both from where we’re at now,” Sibla said. “So it’s not a situation where we’re working with the parameters that we’re at now. It’s a situation where you would see growth in both. But what is that best ratio of the two that makes the most sense for the racing product.
“We’re not yet to that stage, but that would be what would happen quickly after we say, ‘OK, this is the group that maybe we haven’t made a final contract signing, but this is the group that we want to go deeper into understanding their solution.’”
The current MGU made by Empel is actually capable of being dialed up to contribute more than 100hp upon deployment, but the Version 1 ESS can’t hold a charge that’s big enough to deliver that kind of power for more than a flash.
The Version 1 MGU has been held in the 60hp range for the sake of reliability as well, and with what the series is thinking for the 2028 car, a more powerful ESS that can push the MGU harder with a base power output over 100hp would be the starting point.
“The current MGU, which is developed by Empel, has a lot of room left in it in terms of that horsepower,” Sibla said. “It probably is closer, in the right circumstances, to giving 100 to 150 horsepower, so you’ve got the room in there. It’s really been limited by the ESS, and that’s only because of what we touched on earlier, which is the size of it, but the MGU that we currently run definitely has that increase being capable.”
Whether the Version 2 hybrid would go to an all-new MGU, use a modified version of the Version 1 MGU, or simply stay with the same Version 1 model and tap into its unused triple-digit power capabilities is unclear, but the general direction for Version 2 is simple: More battery storage equals more available power.
The series is also contemplating whether it wants to end the practice of having two push-button power-adders at the disposal of its drivers. The hybrid is available at every race, and on road and street courses, IndyCar allows extra turbo boost through its Push to Pass system. In 2028, the ERS might be the only item to engage from the cockpit.
“We have looked at whether the hybrid system is an augmentation, or potentially, in the future, replacing Push to Pass,” Sibla said. “What we have to look at is, what horsepower increase do we want the boost to be? What do we want that ratio to be between the internal combustion engine as well as the hybrid? Do we want it to just be all hybrid or a mixture of the two? And again, the more you increase that MGU power output, the more that ESS duration comes down. So, what is the best blend between that power and the duration?
“The current system could go much higher in power, but it would be such a short duration. It wouldn’t have much of an impact. So that’s the balance. But when you come to the MGU itself, it definitely has the capability to go much higher than where it’s at in terms of horsepower.”
IndyCar intends for its vendors to have the Version 2 prototypes ready for the onset of new-car testing.
“It would certainly be something that we would aim for next year,” Sibla said. “Both groups have products in mind that are certainly bespoke solutions to us, but the technology is not unknown to them. So in a perfect world, and this is what we always aim for, I think you’d be talking a late spring prototype.
“Ultimately, we want the hybrid system in the car for that prototype chassis testing so that we have an accurate sense of all facets of the car. The weight distribution, the power that we’ve talked about, and the way that everything is working with one another.
“So our goal would be late spring, at least in the prototype phase right now. From there, you’ll certainly get into multiple tests in which you’re pushing the system a bit harder, understanding any elements that need to be resolved or addressed and so forth, but that would be the timeline.”