A stalemate was the somewhat inevitable outcome from a meeting between Supercars and representatives from Ford and GM homologation teams at the circuit on Friday morning.

Supercars undertook dyno testing in the lead-up to the Great Race to assess the impact of barometric pressure on the two engines.

According to an official report obtained by Speedcafe, the testing showed “a deficit for Ford from the 6300 rpm band and a deficit for the GM below the 5200-rpm band”.

Supercars subsequently proposed a revised air restrictor (51mm replacing 50mm) and camshaft timing for the Ford engine to balance the outputs.

However, under the terms of the category’s Teams Racing Charter, any change to Engine Specification Documents required approval from all teams.

GM exercised its right to deny the changes, having already nodded through aerodynamic upgrades aimed at improving the straight-line speed of the Ford ahead of The Bend.

It’s understood Supercars was still willing to make the camshaft timing change, which does not fall under the ESD, but that offer was declined by DJR.

Ford driver Brodie Kostecki scored provisional pole for the Great Race on Friday afternoon, in a qualifying session where five Fords and five Chevrolets qualified for Saturday’s Top 10 Shootout.

However, Kostecki subsequently slammed Supercars’ treatment of the parity situation in the post-session press conference.

“We need to get our upgrade to fix the deficit to the Camaros,” he said.

“Two kays an hour on average and it’s a bit disappointing that nothing has been done about it after a report has been published.”

Kostecki said the ongoing straightline speed deficit endured by the Fords will make the race “incredibly difficult”.

“At the end of the day the system is pretty flawed,” he said.

“The best way to put it is we’re at the biggest race of the year and it’s like a footy grand final, points are tied, there’s a free kick and you have to ask the other side to miss the free kick to win the grand final.

“It’s pretty disappointing for everyone that’s on the Ford side and it’s going to make it incredibly difficult come Sunday.

“We’re doing the best job we can with what we’ve got, but the motors don’t deg down the straight and tyres do. You can’t make up for what you don’t have.”