[Dominik]

good morning,

as basic as it sounds: it's about airflow, if the mechanicals are okay.
your fans should nor come on at all when you travel at speeds over 30mph.

if they come on, you have to shroud your radiator more. Now yours is fully covered, which is not needed unless you are racing. I feel that underhood temperatures are much lower leaving the upper part of the radiator unshrouded.

that also results in colder feet. Also don't forget, the engine itself radiates a lot of heat, so you need some air flow.

to test your fan's capacity, heat the car up (disconenct the fans) to 210F, park the front of the car near a wall or restrict airflow with cardboard and now let the fans do the work.

that test will cover your stop and go traffic. Temperatur should drop.
Calibrate your water temp instrument!!!

with the radiator nicely shrouded you should be able to travel at 55mph to the next meeting without problems.
if the fans come on (you see that watching the Voltmeter flick for a moment and show a slightly lower reading), you probably have air trapped in the system or a mechanical problem.

keep an eye on your radiator cap, make sure it's not too weak and lets coolant out!

Track racing is a totally different story...
Drag racing: travel back to the pits going moderately fast to improve airflow through the radiator.
Chassis Dyno: you need a very strong fan to simulate airflow at 130 mph +, if you measure in 4th gear at max RPM.

also: make sure your ignition is not too retarded at low engine speeds.
an indicator for this are red hot headers at idle or slow vehicle speed, or melted hoses!

got the idea? :-)

dominik