The problem is that the crash forces go up cubed. If the cars used to run 100 mph and suddenly you allowed mods that made them now go 200 on the same track you have doubled the speed but the forces in a crash go up by a factor of 4. If you hit the wall at 100 mph and get 500 ft/lbs of energy directed at the driver once he is going 200 mph and hits the wall he is subjected to 2000 ft/lbs of energy. The energy numbers are just for comparison and not actual numbers that a wreck may generate.
So it may seem like the difference between 180 and 210 is only 30mph but the energy is increased dramatically.
If this is confusing it's because I'm tired and can't think straight.
90 degree V6's have been tried in BGN and proved to be unreliable. I used to think 275 or 300 cube V8's was the answer but I don't really know. They would just turn them 11,000 rpm and probably go just as fast as today. We do need to bring back the old days of Cale Yarborough {sp} doing the draft pass coming off 4 to the checker. Now days they would just block like mad.
500