About 8pm
We went last weekend, 8/19/17. The gates opened at 6pm Eastern time. They started qualifying each division around 7 pm. The hot races came next around 8. (We know them as "heats".) As soon as those were over, they started racing. It was over around 10pm. Sorry I don't have exact times, but as you probably know, it really depends on how many cars are racing and caution flags go out. Hope this helps!
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