Ambient temperatures in the mid-30s saw cabin readings push through the 50 degree barrier as drivers attempted the back-to-back 100km races during the afternoon.
Cabin conditions have been made worse for the drivers this year due to the engine moving closer to the firewall under the new-for-2013 Car of the Future regulations.
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Some drivers needed to be helped from their cars after enduring cool suit issues in the first race – a worrying site with less than an hour to recover prior to the second encounter.
“I was saying to the boys after the podium that it was probably a top five as far as cabin temps go inside the car,” said Whincup after Race 14.
“We were absolutely spent after the first one and wasn't sure how we'd back up for the second.
“We cooled our cool suit down uncomfortably lower than the first race. If you go too far it obviously freezes up so we ran it on the limit there and tried to get more air into the helmet and got through the second one.”
Although stopping short of critisising the scheduling, Whincup believes that the idea of mandatory air-conditioning systems should be revisited.
“I think they (V8 Supercars) like people passing out,” he said when asked of the limited recovery time.
“I've got to be careful what I say, I don't want an OH&S issue, but I think there was just enough time to cool our core temps back down and then go again.
“But without doubt we're getting real close to the stage where we're going to have to run air-con or have to change the system.
“The way the rules are we've got to run a light weight cooling system because it's too much of a disadvantage running something heavier.
“It's getting to the stage where they just (should) run an air-con pump on the front of the engine mandatory for everyone and it'd be much cooler.”
Victories in Races 13 and 14 today have lifted Whincup's season tally to five. He now leads the championship standings by an extended 113 point margin over Will Davison.