I took the car for a test run. From a cold start (24+ hours off) to a warm engine (181F) took 3.2 miles. Yesterday it was just over 4.2 miles.
This run was 1.5 miles to a stop, I got up to ~50MPH, then I coasted for the last .6 or .7 of this. Then another 1.5 miles to a stop, same coasting. Just after the second stop it was up to temp.
So the lower grill block speeds up warm up from 4 miles to 3 or 1/4 shorter. No grill block (upper or lower) warm up is about 5.5 -6 miles. With both grill blocks I have halved my warm up time
I also saw how long it took to for the fan to come on, on my car it comes on at 206F. This took till mile 8. Even with the grill blocked it can drop the temp from 206 back to 195 in about 60 seconds. I know that my belly pan does not have a tight fit to the underside of the car, so the fan can pull some air up from the bottom. Not much to pull from but it is nice to see that it still will work if needed.
Next time I do some ABA testing I will have to see how much MPG I gain from having it closed. I will have to open it some of the time, but I can do it while I am coasting (lessens the MPG loss). On longer trips I will likely need to open it, but I will have to see how far I need to.
I plan on setting it up for full open or full closed, but I can change that if needed. Or I can just unplug one actuator and leave that side open or closed.