Starting with an engine water temp of 194, with the grill blocked, at the end of each run, water temp was up to 230 when turning onto the second turn-out; it rose to 244 while waiting to get my timeslip.
With the grill opened to a 3" X 12" opening, water temp rose to 199 at the second turn out and rose to 207 while waiting to get my timeslip.
Unfortunately, I do not have a good same-day comparison of mph. On day one with a small tailwind, the car went 174mph with the grill blocked. It went 167 on day two with the grill open, but we were bucking a really big headwind. Speeds were off enough on day two that most competitors went home early. I will try to be more systematic with my research in 2016.