Hi guys I wonder anyone can help ?

I have a 415msx mre and I am running 6 cell nimh's, 4.0 brushless motor with foam tires on a asphalt track, I am having serious belt issues, everytime I take the car out it strips either the front or back belt ! I have tried the std belts and the low friction belts none last !! is this because the car was not designed for this horse power or what ?

or is there other belts that I could fit that will work ???