I saw that Ken, and this is your area of expertise not mine, but I'm not talking about the spill plates. My thinking is that with less traction I might add another half a degree or degree of wing in an attempt to keep the tire speed under control and I think that would offset or at least minimize the tire growth. In a Funny Car I would raise the tailgate just as they have done for years to combat summertime track temp.
Am I looking at it wrong? Not trying to argue, trying to learn.
Alan
Alan, it's a balance of everything to get the result you are looking for. The chart below might help explain why a little bit better. Every inch of tire growth helps (a bunch) with speed at a given RPM. While any amount of wing counteracts that with drag and downforce (which compresses your tire diameter). Without giving away exactly what I do, last year in Las Vegas (2000ft), I added a little wing angle because the altitude is a bit higher and we still went 329MPH. This year in Joliet (600ft), I left that same amount in the wing because of the track prep changes and we only went 324. I'm sure there are other factors affecting that as well. The key is to realize that every change you make has consequences elsewhere and to try and get a handle on all of that. The only other thing I want to add to all that is there is one guy that really impresses me because he seems to understand ALL OF IT. That guy is David Grubnic!