Add American V8 preset, carb fuel transport, and adaptive desktop audio

include/FluidSim/Atmosphere.hpp

@@ -31,6 +31,7 @@ private:
         port.temperature = temperature;
         port.enthalpy = specific_enthalpy();
         port.air_fraction = 1.0f;
+        port.fuel_fraction = 0.0f;
     }
 };