The two manufacturers are represented by sister brands Cadillac and Acura, respectively, in the IMSA SportsCar Championship, where they just completed the maiden season of a hybrid-infused GTP class over nine races in 2023.
In the build-up, the series allowed each manufacturer to create its own powerplant, with rules in place such as a total system output (gas plus electric motor), which could not exceed 500 kW (671 horsepower). Additionally, per Section 5.2.1 of the 2023 IMSA Technical Regulations, the ICE (Internal Combustion Engine) speed limitation was set at 10,000 rpm.
The total output of the ICE and ERS was established between 480-520 kW (644-697 horsepower), and that was measured at the driveshaft by torque sensors and subject to BoP (Balance of Power) adjustment.
Cadillac developed a 5.5-litre naturally aspirated 32-valve V-8, while Acura opted for a twin-turbo 2.4-litre V-6.
The development in IndyCar is dramatically different, with both Chevrolet and Honda more in collaboration of a single unit that fits both respective 2.2-litre engines (V6), which debuted in 2012. The initial hybrid concept was developed by Mahle prior to being taken over by the manufacturers.
Depending on the track and if the 60HP push-to-pass boost was available, the horsepower ran between 550-700 in 2023. With the addition of the hybrid system, that number could jump an additional 150HP.
With so many factors, a flurry of testing has seen thousands of miles logged at a variety of different tracks throughout the year, with the heaviest workload currently in effect – and has been since the checkered flag flew on the season finale at Laguna Seca on Sept. 10.
David Salters, President Honda Racing Corporation US, shared how building up a hybrid system in IMSA, among other places, has helped the process of development for IndyCar.
“I think we've all been learning for years, either through our production side of electrification and we have experts that we bring in from our production side,” Salters said. “We have experience in Formula 1 and then we have experience in IMSA and you just constantly are adding to your knowledge bank.
“It's a new technology. It's interesting, energy management is very relevant. All these sort of things, we are helping actually develop the system, so that's a new challenge that is completely different from LMDh. It's different, to be straightforward, but of course you've got all this acquired wisdom and you try and use it. Not always, but you do try and use it.”
Mark Stielow, the Motorsport Competition Engineering Director for General Motors, added: “I mean, they're similar but different. So, the IMSA side is high voltage. IndyCar is a little different than that, but the people working on it and optimising it are similar.
“Like David mentioned, I'm able to dip into our production side of the operation and get the learnings from electric. We have a lot of electrification going on inside General Motors, as does Honda, so we're able to kind of use those learnings and push 'em back and forth. So, it's going to hopefully, bring some buzz to IndyCar like it has done to GTP and get some more fans pulled in on the IndyCar side also.”
Following two days of testing at the Indianapolis Motor Speedway last month, Rob Buckner, IndyCar program manager for Team Chevy, noted how the collaboration with a rival manufacturer, particularly Honda, isn’t as uncommon as it might look on the surface.
“It's not as awkward as people think because it's easy to overlook,” Buckner said.
“General Motors and Honda are developing fuel cells together, electric vehicles together. This isn't our only joint venture, if you will. Still compete in the showroom, compete on the racetrack, but this is a project that teaming up together has made a lot of sense. It helps the series that we're competing in. It's been a good joint collaboration project.”
By now, several items have been agreed upon and finalised, according to Matt Niles, the Honda Hybrid project leader.
“We’re pretty set on where we are with the energy storage,” Niles said.
“I think we've been finding out how all these different components survive in this environment. The vibration is unique. Also, the temperatures that we deal with. We've been learning a lot about that.
“But I think going forward, a lot of it is really how we use the system and the parts and pieces we have, and how that's regulated on track and how the drivers use it, how the engineers interface with it, how we go racing. That's where we've been going through sort of street course at the short course at Sebring, we've been running short ovals, road courses, and now we're here at this hallowed ground to see how it works here.
“We just kind of have to go back through all the data, start making some decisions on how we go to St. Pete.”
