This week’s three-day IMSA test at Daytona International Speedway will feature approximately 30 cars in attendance from all four WeatherTech SportsCar Championship classes, and in a new twist, the series will be doing more than trying to gather Balance of Performance data to use for January’s Rolex 24 At Daytona.
The main emphasis for IMSA’s Friday-Sunday outing is the new application of torque sensors on the supercars in its GT Daytona and GT Daytona Pro categories. Implemented by IMSA in 2023 within its hybrid Grand Touring Prototype cars, the series is expanding the deployment of torque sensors beyond GTP to include all GTD models in 2025 as a method of improving BoP information gathering and governing methods for its GT3-based field.
Torque sensors serve as miniature chassis dynamometers attached to the rear axles which feed constant performance information — horsepower, torque, and acceleration curve data are among the key channels — to the series through telemetry, and highlight any related BoP violations that are detected through the sensors.
With such great variance in the layouts of its GT entries from Aston Martin, BMW, Corvette, Ferrari, Ford, Lamborghini, Lexus, McLaren, Mercedes-AMG and Porsche, IMSA’s technical staff will rely on the torque sensors made by Magcanica to better balance the array of front-engine designs with inline turbo six-cylinder motors, front-engine naturally-aspirated and turbo V8s, mid-engine turbo V6s, mid-rear-engine flat sixes, mid-engine naturally-aspirated and turbo V8s, and mid-engine naturally-aspirated V10s from track to track.
Through its BoP modeling for each car as a tool to create parity, manufacturers are given performance turning parameters to play within, and with torque sensors, the series is able to track each car’s engine output and acceleration figures from corner to corner on every lap. The sensors also act as electronic referees, flagging any breaches of the BoP limits put in place by IMSA as they occur.
The decision to carry over the same torque sensors from GTP to its GTD and GTD Pro cars also means the series brings exceptional familiarity to the use of the units in competition, but that’s not the case for most GT teams and manufacturers in the WeatherTech Championship paddock, which is why the series is using the November test at Daytona as an opportunity for its GT entrants to learn about the sensors during the numerous test sessions.
“One of the primary things we were trying to accomplish was an ability to get the GTD and GTD Pro cars on the racetrack, to provide the manufacturers, the teams and IMSA, an opportunity to see this new technology integrated into their cars,” Matt Kurdock, IMSA’s director of engineering, told RACER. “It’s a fundamentally different way that the powertrain will be regulated, and we felt that it’s a significant enough of a technical regulation change that it would be beneficial to provide the opportunity get the get the cars on track with adequate time to address any issues prior to the Roar Before The 24 .
“Not only will some of these systems be used for the first time by some of the teams, but we also need to make sure that all of the monitoring and regulating electronics are working in conjunction with the with the updates the manufacturers have done to their cars. We like to call it a ‘systems integration test,’ and we will have the opportunity to then work throughout the event to address any issues that pop up. But also if there’s anything that IMSA or the manufacturers need to address before the roar, there’s some adequate time to look into it.”
With the adoption of torque sensors across the two GTD categories, IMSA will drastically alter its usual engine BoP adjustment techniques for aligning vehicle performance along with bringing in a new two-tier BoP table.
“When we did this before, we would regulate power through air restrictors and boost limits as a function of engine speed, and we would set the maximum fuel capacity,” Kurdock said. “Those three things go by the wayside now, and we’re going to regulate power to a maximum power curve, defined as not only a function of engine speed, but we are going to implement something called two-stage power.”
Based on the shape of the car — some being low-slung while others are tall — or the different manners their respective engine architectures make power, the range of GT machinery has inherent strengths and weaknesses at each IMSA circuit.
At Daytona, for example, a waist-high Ferrari 296 would be more likely to smoothly cut through the air and achieve a higher top speed on the long straights than a chest-high sedan like BMW’s M4, and with the new two-stage BoP power approach, settings in the second stage can help address any advantages or shortcomings as cars near maximum velocity.