Looking for Input: 370 Motorsport Data Logger

MotorvateDIY

It is a stock 2011 G37S, 6 speed manual with Stillen cat back exhaust. It has the non-pressurized coolant tank. The rad cap shows pressure rating of 137 KPa or 20 psi.

On the second test drive, the coolant temp was 82C / 180F and I did a WOT pull in second gear to 7500 RPM. Max coolant pressure was 27 PSI at 6662 RPM. It then dropped to 23 PSI at 7575 RPM and the coolant temp dropped to 78C / 172F.

I wonder if the pump started to cavitate?

This 4°C/7°F coolant temp drop also happens in the summer, with the engine fully warmed up.
I have a log from last summer and it did the same WOT / 7500 RPM temp drop (4°C/7°F) after driving for 40 minutes with coolant temp at 88C / 190F and oil temp at 95C / 203F.

By the way, this temp drop will never be noticed with the factory coolant gauge/dots. The gauge cluster is programmed not to show any temp change between 70C / 158F and 115C / 239F. This is a common strategy to prevent people from freaking out if the coolant gauge moves and tying up the dealer's shop floor when everything is OK. (even though the coolant temp does change quite a bit depending on operating conditions)

Now that I've verified there are no leaks, I'll be doing a few longer test drives today.