Improving AC?

That is not totally true. Water boils at 212. Higher with pressure. The ethylene glycol does not chemically bond with water, the molecules simply intermingle leaving H2O free in the system. Mixing offers a bit worse heat transfer since the antifreeze is much worse than water at transferring heat, but the water will blow off when it hits 212 (at sea level) regardless of the other stuff mixed in. If you want to see an easy example, mix salt and water and put in a pan. At 212 water will start to disappear. Maybe not quite as fast as pure water, but it will boil away. Yet salt is a perfectly viable antifreeze solution except that it is too reactive with iron or aluminum, where EG is not.

The trick is to separate the H2O molecules so that they can't attract each other to form ice. And that same trick serves to inhibit boiling. But inhibit doesn't mean "completely stop". I would NEVER want to see my coolant temp at 230-240 which is still below the boiling point of the mixture. And I would certainly never remove the radiator cap at anything above 212.

If you believe it won't boil at 212, take your truck for a 30 minute drive and then remove the radiator cap.

There's yet another issue. When a gauge measures 200 degrees, that is the "average" temp of the water. It is going to be significantly hotter when it is very close to metal surfaces near hot spots such as around the cylinders on in the head. And it will definitely flash to steam given the chance, even if those bubbles are re-absorbed shortly. Relieve the pressure and poof...

 

honestly i doubt those temp readings are accurate. Intake air temp of 177*f is 20* hotter than anything i ever say with my WARM air intake experiment on a 95* day pulling air from directly under the hood across the exhaust manifold in stop and go traffic.