If you want to get around the limits on O2% in atmospheric air, how about switching to a fuel with a lower (than 14.96) stoichiometric AF ratio? That way you'll require less air to burn the charge - the tradeoff would be in the LHV for the fuel (often a lower stoich AF means less bang per molecule). Perhaps you'd want to try a mixture of Methanol and Nitromethane? I think you'd find that to be quite sufficient for getting your kicks. :frog: