Hi,
Of course there's a "speed limit" in F1. Why do you think they mandated grooved tires years ago, put chicane's on the straightaways, eliminated traction control, modified the tracks, etc? To keep the speeds under control! F1A is famous (infamous?) for changing the rules all the time, sometimes for speed, sometimes for safety and sometimes because Bernie wants it that way! Not sure about IRL or Champ cars, don't follow them anymore since Tony George destroyed open wheel racing in the US years ago, but F1 and NASCAR will do whatever is necessary to keep the speeds below 200 MPH. There's that number again!
BRG,
Jon