Rahal was speaking after a 20-car group test at the Milwaukee Mile on Tuesday, where each car was equipped with the new common hybrid unit that is set to make its official race debut July 5-7 at Mid-Ohio Sports Car Course.
Hybrid testing first began in August 2023, and development running was then shared between engine suppliers Chevrolet’s (Arrow McLaren and Team Penske) and Honda’s (Andretti Global and Chip Ganassi Racing) powerhouse teams.
But the series’ smaller outfits did not get access to experiencing the system for real until a test at the Indianapolis Road Course in March of this year, which included Honda-powered squad Rahal Letterman Lanigan Racing.
Team Penske swept to the top three fastest times in the Milwaukee test, followed by cars run by Andretti and Arrow McLaren.
“I think the teams that got all the hybrid testing flat out… I don't care what they say, it's a huge advantage,” said Rahal.
“There's so much to change: manual regen, auto regen, how much regen, what's the gain, what's this, what's that. It's the opposite of F1 where it's pre-programmed and the driver just drives.
“Here the driver has to do the majority of that. Sometimes you can go to auto regen, but then you have to use the paddle to get extra state of charge.
“It actually does affect the way the car handles a lot. You're trying to balance that, too, right? I think this is easiest for me on a personal level, but it really didn't work for my car balance. There's a lot of things that do change.
“There's a lot to learn. There's a hell of a lot to learn in a very short period of time, unfortunately.”
The much-delayed hybrid powerplant will feature additional overtake (push-to-pass) options that will allow drivers more choices and control, which is expected to enhance the on-track competition.
The system is made up of the low voltage (48V) motor generator unit (MGU) and energy storage system (ESS) – consisting of 20 ultracapacitors – both of which fit inside the bellhousing, located between the internal combustion engine and the gearbox.
During regeneration, acting on the clutch shaft, the MGU builds power to be stored in the ESS. The additional horsepower is deployed through the same motor generator upon driver demand.
For competition, options for automatic regeneration will happen via braking or throttle position, with manual regeneration via selected steering wheel paddles and buttons also available. The deployment of the stored energy will only be available manually, which will happen through a latching button that is like the current overtake system.
Rahal said that the 160mph average speeds around Milwaukee’s mile made it tough to assess the hybrid’s impact.
“For me, today it was a bit of a zoo trying to figure it out in a short period of time,” added Rahal. “You're so focused on the driving aspect on a short oval like this that I think it makes it difficult to maximize the effect of the hybrid.
“There's a lot happening. This is a very low-grip track. You're sliding around so much, too. Not the easiest thing to do to remind yourself constantly to hit the button. I think in the end, as it does become second nature, it will be fine. We just got to give it a little bit of time to develop.”
The test included some race simulations, when the field was divided into two groups for cars to run closely together.
“On the simulated restarts we were doing, when you utilize it, it's a clear boost,” Rahal added. “I would also say in traffic when you get really bogged down, it was nice to be able to pull the deploy and really feel a lot of gain.
“That can make racing quite interesting, I think. As challenging as it is to remind yourself of it all the time, I think the net effect is going to be positive.
“When you're up doing a qualifying lap, high in rpms, the feeling is really nominal. But, as I said, coming off the corner, low rpms, race running, things like that, it's quite a large effect, which is cool.”
