Parity Changes in Play as Supercars Fires Up at Symmons Plains
By Andrew Clarke
Date posted: 9 May 2025
Supercars has enacted fresh engine calibration updates for both Ford and Chevrolet, just as on-track action begins at Symmons Plains. This move aims to iron out temperature-based performance variances exposed during recent technical reviews.
The changes — implemented following category dyno testing and signed off by both homologation teams — are already active for this weekend’s Tasmania SuperSprint and will be closely watched as the parity debate simmers once more.
While the Mustangs have won six of the opening nine races, Ford teams have been concerned about losing power under certain conditions, particularly when cars are buried in traffic or dealing with heat soak on warm days.
The latest updates stem from a Supercars investigation into inlet air temperature and its influence on engine behaviour. The results confirmed that the GM and Ford platforms responded differently depending on ambient conditions.
Speaking trackside at Symmons Plains, Supercars’ Head of Motorsport Tim Edwards told Auto Action the changes were data-driven and aimed at restoring fairness.
“We’ve always said we’ll respond if the evidence supports it — and in this case, the data showed the inlet air temperature had a measurable impact on each engine,” Edwards said.
“We’ve worked with MoTeC to deliver a smart calibration that adapts based on real-time airbox temperatures. It’s not something the teams can adjust — it’s built into the software — but it helps keep things balanced in changing conditions.”
Supercars recently tested the engines with different inlet temperatures, like the sort of variations experienced in traffic, and created a tool to tweak the mapping to retain parity. Image: Peter Norton
The study revealed that temperatures below 25°C—the standard temperature used for parity testing—offered a marginal advantage to the Ford engine, while warmer conditions slightly favoured GM’s pushrod unit. This meant the Chevy had better performance in traffic, where the inlet air was warmer. The new software essentially levels that out by adjusting the calibration curve automatically.
After baseline testing at the different temperatures, the tool will also be employed on the Toyota next year.
It’s the latest in a long string of parity initiatives, following transient dyno testing in the United States last year and aero balancing work across the 2023/24 off-season.
Despite those efforts, the parity discussion refuses to go away, particularly as results have varied track to track, and questions continue to swirl about whether team execution or technical imbalance is to blame.
Last year’s Symmons Plains round was one of the rare Gen3 weekends where both Ford and Chevrolet scored wins, and with the new mapping now live, all eyes will be on whether that balance carries into 2025.
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