Here's a question on fans, I've seen both open frame dual fan setups and closed frame. The closed is really a flat panel with 2 holes in it for the fans. At low speeds I can see the closed style pulling in more air with both fans pulling. What about at highway speed? Does that panel create an air block reducing the cooling b/c the volume of air going through those 2 holes is reduced from the open style? I assume it would also create some drag by the resistance of air flow though the grill.
yes and no. If the flow area of the holes are greater than the flow area of the radiator, you're probably OK. Keep in mind, the radiator might have several square feet of area, but when you subtract the area for the flues and fins, it's much much smaller. Also the flue are designed to cause drag for more efficient convention to the airstream. What I don't like about the shrouds that use holes like that is they direct the air to be biased where the blades are. The outer areas won't cool as much and during speed they won't flow as much.
That being said, the only time any of these 'issues' will be a problem is if you're taxing the hell out of your cooling system. If your average use is around 100% of it's capacity, you're going to have issues. All it will take is an extra hot day, extended idle times, etc....
If you're cooling system is in good shape and not handicapped, idling should need a 100,000 CFM fan from hell. Sitting still the engine is making just enough heat to idle and slosh through the torque converter. It doesn't take a whole lot of cooling capacity to reject that (baring you live somewhere that introduced a new factor like a mile high desert)
I live in GA. It's 100 degrees outside right now and the Summer's just getting started. My cooling system consists of an F-body radiator, Advance Auto Parts water pump, a Vatozone heater core and an external trans cooler.
My temp stays rock solid and if I kick the crap out of my car the temp actually drops a smidge. I have a powerloger file showing that on a laptop that has no screen. It was posted on this site somewhere but I can't find it.