Ed brings up a very good point as well, the coolant flow is dropping. Once again .....transients!

The reason for cars requiring large diameter rad hoses is now less muddy in my muddy fuddled brain.

Boy Racer on the throttle to the next stop light. Lots of heat load followed by idling at the light in 110 deg weather with the AC running.

No similarity to continuous operation.

There goes the argument for 2 in rad hose and a Mac truck radiator in an airplane.

Steady state data is key here.

Now I am going to bed.

Monty