This was/is the track I was mostly running at. I can't find a video of the 4w class, this one is 2w and supposed to be 17.5 no timing, but I'll be damned if I'm the only one who doesn't have a 13.5 or more. 540's here are no bueno. No, this isn't my video, and yes I am in it, and yes I won.
Anyway, this is the smallest track I run on. It is a sandy clay loam, hard packed with a loose top layer AND it will start to break up if it gets watered wrong. And it will thermal a 6.5 540 in six minutes geared 62/13 with no timing. Sucks because I think it would be faster because it's easier to drive than the 550 given the traction, IF I could get over the heating issues.