Last 2019 track day for Caf & Gas at Hallet Motor Racing 11/13/2019. My PS 4s are heat cycled and hard as hockey pucks. Very little grip; so, I know my turn entrance and exit speeds are not optimal. Then I notice on the straights I am achieving 5MPH more than I ever have. So can I get some estimates on just how much horse power I gained from the ambient air temp. It was 28 at 9:30 when I started session 1 and warmed to 40 by 11:30.

 

5 mph trap is a pretty big jump on the straights. Are you sure something else was not different? Your exit speed, where you were braking etc.? Usually 5 mph trap increase means around 30 - 40 whp increase. That is a pretty big jump considering nothing changed on the car other than the ambient temperature.

 

I don't have any proof, but my RCF feels way faster on a cold winter day here. California cold like 40 to 50 degrees compared to the 90 to 100 degree summer days.

 

Found this searching the net http://www.csgnetwork.com/relhumhpcalc.html. Using yesterday's data I could theoretically have had 5.2% more horse power compared to the previous track day 10/09/2019. Wow!