Being a pylon racer.... and by this you mean that it will actually be used for pylon racing and not just as a scale model ... then you need an airfoil that has some camber to allow for tighter turns without reaching too high a lift coefficient where the drag piles up. But at the same time you want an airfoil that still shows low drag coefficients at Cl's of around zero since a lot of the time in the "straights" between turns you're going weightless and therefore have zero lift. So you want an airfoil with some camber but not too much and with a thickness that meets your rules. Without the rules you're operating under there's no way to pick an airfoil for you.

A good place to start would be the Martin Hepperle website where he's done some airfoils intended for racing and higher speed applications.

http://www.mh-aerotools.de/airfoils/...ylonracing.htm