The first blog in this series covered the reasons why Indycar needs to move to a hybrid formula with their next specification in 2021 or more likely, 2022. Most of those reasons were business. And they should have been crystal clear to Indycar leadership when Porsche offered to join the series, but ONLY if there was a commitment to a relevant formula (hybridization in this case).
In this second and last article in the series, we are going to talk about how this might be done.
Hybridization in racing has been around on Road Courses and Street Courses since at least 2009. In that year the FIA allowed it in Formula 1 as KERS , which stands for Kinetic Energy Recovery System. In 2014, F1 allowed more complex hybrid systems that include an MGU-K system (very similar to KERS ) as well as an MGU-H that works in conjunction with the turbocharger.
KERS/MGU-K —In a KERS or MGU-K system there is a motor-generator of some kind in the drivetrain, usually between the engine and the transmission. The motor-generator is also connected to an energy store. The energy store can be a flywheel, a battery or a capacitor. When the driver steps on the brake or otherwise slows the car, the motor-generator slows the car by applying resistance that generates electricity, which is stored in the energy store. This is called regenerative braking and feels a lot like engine braking. When the driver hits the accelerator, this energy in the energy store is used to spin the motor generator and assist the engine in accelerating the car.
MGU-H—The MGU-H is a motor/generator located between the impeller (hot side) of a turbocharger and the compressor (Cold side). An MGU-H would likely not be feasible running at nearly full speed on ovals, so we are going to concentrate on KERS-type systems.
The basic principle that makes hybridization practical is energy recovery and use. In simple terms, a KERS system takes energy that would have been shed when a driver slows the car down and turns it into stored energy that can be used to accelerate the car. This requires the cars to change speeds regularly.
Car design considerations
Adding KERS to an Indycar would be relatively easy. An off-the-shelf racing KERS system would work. These are available from providers such as Xtrac (which makes the transmissions Indycar uses) and HPD-partner Magneti-Marelli, among others.
As far as space, the motor-generator would be located between the engine and the transmission or integrated with the transmission (they are about the size of a torque converter). The energy store would probably have to steal space from the fuel tank. But we would assume that the fuel tank for a hybrid would be smaller to reflect higher fuel mileage. So fitting the components is a minor chore.
Tackling the oval issue
Hybridization would not work in Indycar today. The reason is the speed of the cars does not vary enough. Indycar has five races on ovals: Texas, Iowa, Pocono, Gateway and the Indianapolis 500. Of those, Gateway and Pocono would be easier to deal with than the other two. On those two tracks there is significant change of speed during a lap even today, to the point where drivers must lift off the throttle to make the corners, and in some cases downshift on every lap.
The real problem track for hybridization is Indianapolis. The fastest way around is flat all the way. To make hybridization work you’d have to change the aerodynamics of the car such that drivers would have to lift off the accelerator going into Turn 1 and Turn 3. Or you would have to design the hybrid system to be easily removed for ovals that would not use it. You also could use the hybrid system sparingly. Let’s look at those options.
*Removeable Hybrid system—*I would dismiss this idea pretty fast for two reasons:
- Any car that would be designed to have its hybrid hardware removed would be compromised in other areas. On ovals the car would be larger than it needs to be with voids where the hybrid hardware was that would be less than optimal from a structural standpoint.
- Manufacturers would want to show off all their latest technology advances at the biggest race in the series: The Indy 500. Which is an oval. Removing the system is a commercial non-starter.
*Limited use of Hybridization—*In this case we would make no changes to the existing cars other than making the hybrids fit. The energy stores would only be charged when the brakes are used. At Indy that is limited to entering the pits. This would result in limited use of hybrid energy during a race. Again, from a commercial standpoint this is a non-starter.
*Change the car design—*This is the path I would go down. From the stand point of simple physics, I would make the cars faster on the straight and slower in the corners.
The simple problem with modern Indycars when it comes to hybridization is that they go around corners too fast. Indycar drivers don’t have to lift off the throttle going around corners at Indy. The cars top out at about 238 MPH entering the turns and are slowed to the high 220s through the corners. The cars slow down by scrubbing off speed through the tires as they turn. For hybrids to work, this would have to change.
The way to do this is to lessen the amount of drag and downforce the cars carry on ovals. Perhaps the target should be 200-to-210 MPH in the corners. Such changes would also likely increase the top speed on straights through reduction in drag that would come with removal of downforce. The object of the exercise is to make the drivers lift off the throttle going into corners.
There probably has to be 30-to-40 mph difference from top speed on the straight to speed through the corners. From a hybrid standpoint, that would probably be enough to get some regeneration twice a lap at Indianapolis. Think of it as a replacement for engine braking.
So in a hybridized Indycar, drivers would accelerate up to about today’s 240 or a little higher on the straight, but the top speed would happen sooner than it does today. In order to make the corner, the cars would have to slow down before entering the corner. This would likely be done by lifting. The hybrid system would then act like an engine brake and slow the car down while charging the system. The drivers would accelerate out of the corner, in some cases with the aid of hybrid energy.
The technical challenge is to make the electric power boost effective at the speeds you have around Indy. Most of the time hybrid power boost is most effective at slow speeds, like charging out of a corner. So we are talking a range from 20-to-80 MPH . To work at an oval like Indianapolis, it would have to have a positive impact at 210-230, or whatever speed the cars are running coming out of turn 2 or turn 4.
Overall, the Indycar KERS system would have to work for all speeds up to about 230.
So are hybrid power trains feasible for Indycar? Sure. Is it the smart way to go from a business standpoint? No question in my mind. Will they do it? As a long-time fan who wants the series to succeed, I hope so.