Scrutineering is central to motorsport, and always has been. These safety and technical checks are an important component of any event: they take place before the cars go out track, continue over the course of the competition and on through to the aftermath of the race. In the modern, high-technology world, scrutineering has become ever more sophisticated and today in the WeatherTech IMSA SportsCar Championship Bosch Motorsport plays a key role in the process.
“Scrutineering happens multiple times over the weekend,” explains IMSA data and electronics engineer Emily Rivera. “On the very first day of the race weekend we will have the safety inspection to make sure all the safety components on the car are functioning. After that we will do the technical inspection, and then after every session the top cars will come in for a check. They are required to come in, but each team also has three voluntary tech inspections.”
These technical inspections include scanning the bodywork surfaces of the cars in three dimensions to ensure they comply with their homologation. The specification of an LMDh prototype racing in IMSA’s GTP class is fixed when it goes through the homologation process and must not deviate from that form when it hits the track.
The teams are given what is called a “heat map” after this process, says Eric Haverson, Director, Technical Compliance and Scrutineering at IMSA. “We have tolerances — some are higher and some are lower — and the teams can see how much out of tolerance they are.” This transparent process gives the teams a chance to “fix anything that is out of spec”, adds Rivera.
What might be termed more traditional checks take place during the technical inspections. Rideheight, rear wing angle and suspension camber are among them. But it is also a time for ensuring that the Bosch scrutineering system, which is central to IMSA’s GTP and GT Daytona classes, is functioning properly.
“Bosch will plug in and make sure all the sensors are working and calibrated properly,” explains Rivera. “If there is any problem, they can let the team know before they get out on track.”
Alex Simone, Bosch Motorsport engineer, elaborates: “Safety inspection is our opportunity to make sure everything is configured correctly. When a car ends a race, it gets pulled apart and a bunch of stuff needs rebuilt. Its just a matter of chance that something can be forgotten. We are able to plug into the wiring harness and view on my laptop which sensors are working the way we are expecting them to.”
This also includes the safety systems on the cars, Simone points out. “People traditionally think about belt loops and rollcages when they talk about safety,” she says. “But a lot of the regulations, like the tyre pressures are incredibly important.”
The monitoring of the pressures of the tyres in real time during the race is just one of the data streams flowing from the scrutineering system to IMSA’s technical staff as it strives to maintain a level playing field in the series. “We are making as much effort as possible for there to be a very tight box for the teams to compete in: we want to have a good product on the race track and the best way we can do that is with the data we get,” says Haverson.
“Bosch has been a fantastic partner for a number of years, and in the past couple of years it has bloomed into something so integral to what we do.”
Producing the Bosch system has been a collaborative process between the company and IMSA. “The series says, ‘Okay we want to do X, Y and Z’, and we work together with them,” Bosch Motorsport connectivity engineer Jordan Krell. “They define their requirements, and then we design the system to fit what they need.”
The scope of the Bosch scrutineering system has grown with the introduction of the LMDh hybrids in 2023. “The more complicated the cars are, the more complicated the regulations have to be, which then entails the systems and software in the car being more complicated,” explains Aaron Pfeifer, vehicle technical lead at Cadillac Racing. “Tomorrow we will have more sensors on the cars than today, just as these cars today have more data than in the past,” adds Iain Watt, technical director at the Action Express Racing Cadillac team.
One of the requirements of the scrutineering system is getting data back from the mandatory torque sensors each car runs on the rear driveshafts to IMSA in real time on every occasion they are out on track. They measure the power from the hybrid powertrain at the wheels and also the energy used.
Maximum power, as well as the amount of energy allocated to each car between pitstops, is laid down in the Balance of Performance, the means by which the field is levelled in IMSA to ensure close racing. Effective measurement of these parameters is central to the BoP process.
“We will come away from a race with half a gigabyte of information,” explains Haverson. “The volume of the data and the quality of the data is of utmost importance to IMSA, which is why we partner with Bosch. We wouldn’t have 11 manufacturers across our GTP and GTD Pro classes if there wasn’t parity. That is one of the elements that Bosch provides with its electronics.”
Pfeifer stresses the importance of that parity: “Typically a regulation is a limit and we are always at the limit in racing, so usually you want to push it. Every calculation cycle matters. We want to be on the limit but going over it is an issue. So we have to know what is holding us to that is accurate.”
