Nitro needs less air to burn than gasoline so your gas won't ignite
The amount of air required to burn 1 lb (0.45 kg) of gasoline is 14.7 pounds (6.7 kg), but only 1.7 lb (0.77 kg) of air is required for 1 lb of nitromethane. Since an engine's cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower energy density: Gasoline provides about 42–44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg. This analysis indicates that nitromethane generates about 2.3 times the power of gasoline when combined with a given amount of oxygen.
Now HPI was working on a gasoline 1/8th scale engine though but that kinda seemed to fizzle