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Was on VIR Grand last week, third outing with the car, still getting to know it well.
It was hot, dash showed 95F outside, so I was running my AC. Felt pretty comfortable. Was stuck around 2:54-2:55 and really thought I should be at 2:52. During the middle of my third session I turned off the AC, just for kicks. Next lap immediately went from 2:54 down to 2:51 and hovered around there the rest of the session.
I had figured the AC compressor would disengage under WOT but apparently not.
Talked to someone afterwards and they said if the AC is on in a 981CS, the compressor is always on but that this is "fixed" with a 718CS.
Still have time to find but at least learned something new.
I cannot imagine running with no AC with temps in the 90s. Were you able to get any ventilation without using compressor? Coolsuit? Sometimes I'm not so sure about the fixed windows.
I use a cool suit but VIR doesn’t sell ice when the concession stand is closed. So I was running with windows up in the afternoon. I figured it was worth the chance of a black flag.
So at least for me in my 981 CS, A/C costs basically 1 sec per minute.
My butt dyno could not tell the difference at all, I was surprised to see the 3 sec diff over the almost 3 minute laps. When I have time, I'll have to compare the vmax data.
I just recently designed and fabbed up some window trim pieces made out of ABS plastic and are the same width as the removable polycarbonate windows. If interested in a pair let me know.
05-13-2024, 11:42 PM
981 CS -- AC costs 3 secs on VIR Grand Course
