AllRacing

IndyCar 2028: Engine building options

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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, and how the series could bridge a gap year in engine suppliers. Look out for additional installments in the coming days.

Once the contract is signed to become an official IndyCar Series engine supplier, there are two traditional paths for car companies in bringing racing motors to life. As the series works towards delivering a new engine formula to the grid in 2028, IndyCar has proposed a third path that is being presented for consideration, and if it’s taken, a new business plan will emerge.

The first course is to make its own engines through an in-house competition department like American Honda has with Honda Racing Corporation US. Honda allocates the budget, routes it to HRC US, which then designs, develops, and mass produces a pool of engines to share with partner teams. HRC also provides trackside support for those teams. It’s a 100-percent Honda production.

The second familiar option involves outsourcing the project like Chevrolet does with the specialist racing engine firm at Ilmor Engineering. The project gets the green light from the manufacturer, the annual budget is directed to the contractor where it creates, services, and supports the effort trackside on behalf of the car company. It’s a shared production.

In both scenarios, the engines are proprietary creations, used exclusively to power the IndyCar teams who’ve signed multi-year lease programs, and kept under wraps from rival manufacturers.

Based on recent conversations held between IndyCar and its engine supply partners, the old in-house or outsource traditions could be joined by a fresh approach if Chevy and/or Honda choose to stay and provide the new 2.4-liter twin-turbo V6s.

“I’ve talked to folks about it, and really, there’s three ways that you can go about doing it.” Mark Sibla, IndyCar’s Sr. VP of competition and operations, told RACER. “You can build it internally. You can go to one of the companies-for-hire that will make and handle the engines for you. Or, which we’ve talked to both groups about, is working with a new OEM that wants to join the series and could be looking to get involved quickly or without using the standard paths. What about the groups negotiating with them to use their engine platform in however that’s branded, as an option?

“There’s the opportunity that if a new manufacturer wants to get involved in sport, they could go to a current partner and work a program with them where they’re using a portion, or really, all the way up to their entire engine. And both have seemed open to it, for sure.”

It’s an interesting avenue to consider where an HRC, or Ilmor with the blessing of Chevy, would sign on and be paid to supply and support their own engines for a rival with different badging on the cam covers. The 2.4 Honda could also be a 2.4 for Dodge. Chevy’s 2.4 could be Nissan’s new 2.4, etc. Duplicate branding of the same racing engine would certainly be uncommon, but it could solve the series’ oldest problem.

Chevy and Honda have been vocal for the better part of a decade in calling for IndyCar to find a third manufacturer. Reducing the engine supply burden both companies share – while supporting 27 full-time cars and 33 or more during the Indianapolis 500 – has been a consistent desire, and to that end, HRC and Team Chevy have offered to liaise with interested manufacturers and provide insights that would ease their path into the series. But as they head into 2026, which will mark 14 years with Chevy and Honda as the only two manufacturers involved with IndyCar, nothing has worked to add a new brand to the grid.

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The third option proposed by IndyCar, which could help both brands to generate income and reduce their sizable annual engine supply expenditures, takes the concept of helping a third or fourth car company join the series to new heights.

IndyCar’s leadership is considering several different options for how its 2028-spec engines could be build. Travis Hinkle/Penske Entertainment

“We’ll keep having those discussions,” Sibla said. “And us, from a series standpoint, we’d like to see if it’s something they feel makes sense for them. We’ll just ask them to deliver a proposal on how it would work on their ends, have them agree upon what that arrangement looks like, and we’d work with them to figure out how it would work from our side.

“So when we go and talk to manufacturers, we present those three options to get in and encourage them to pursue whatever works best for them, and that’s another way to break down the barrier. We’ll make introductions wherever it’s needed, and we can at least show you, ballpark-wise, where the cost figures are coming in and then assist them to go and have a conversation, and hopefully come to an agreement with them.”

One of the favorite questions posed by fans is whether IndyCar could adopt IMSA’s GTP engine formula, which allows everything from small V6 turbos, big turbo V8s, and bigger naturally-aspirated motors like the 5.5-liter Cadillac V8s up to the Aston Martin Valkyrie’s 6.0-liter V12, to increase its manufacturer count. Hybrid are also optional in GTP.

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“With my background not being engineering, I ask a lot of dumb questions of our team, and so I’ll say, ‘Okay, why wouldn’t this work?’” Sibla explained. “I say, ‘I’ve got a few ideas as far as why, but take me through this.’ And I think there’s a few things. One, is an IndyCar really is optimized to get as much weight out and to be as lean as possible. Then we talk about weight savings and different things like that, and with their engines, you get to a certain engine size, and quite frankly, it just won’t fit. And usually the challenge is the length.”

In almost every case, the GTP motors are larger in significant ways – longer, taller, and wider – compared to the highly-specific IndyCar V6 turbo formula, which is light, short, and narrow to fit within the missile-like chassis.

The simple answer is with the tight confines of an IndyCar engine bay, most IMSA GTP engines wouldn’t fit. Not unless the spec 2028 chassis was modified for each non-IndyCar engine. Wheelbases would need to be lengthened, and with a longer car, bodywork would need to be elongated and the underwings would need to change, possibly to accommodate wider engines, which would take away airflow and downforce. Taller and wider engines would also have mass that sits higher in the car, which would have negative effects on handling.

GTP engines could be repurposed in IndyCar if the series wanted to welcome a range of customizations and variations that could make those models behave in ways that are inferior to the purebred Indy cars with IndyCar-specific engines.

And what if a manufacturer had something it wanted to bring to IndyCar, and would fit inside the same rectangular space where the 2.4-liter twin-turbo V6s will go, but wasn’t 2.4 liters or a V6? The series’ ears are open.

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“We’ve looked, because I know there are some brands that say, ‘We don’t make V6s, so I can’t sell my marketing department on a V6,’” Sibla said. “So we’ve looked at, can there be potential variations? And there’s still some thought and discussion that needs to happen around that. But what we first have to receive is an outreach, hear about a solution if you think you have something different, and maybe we can find a way to make that work.

“It’s about weight balance. It’s about length and engine size and packaging and all of that that goes into it. Most of the people we’ve spoken with like the 2.4-liter V6 engine formula that we’re proposing and are very receptive to that because it relates to what they’re doing on the automotive side. Otherwise, we will listen, but the size of the engine has physical limitations.”