Jet fuel has a much lower octane rating than gasoline. The octane rating of jet fuel is around 15, which is much more like automotive diesel and thus much more resistant to detonating due to sparks or compression. In contrast, the most common avgas used in piston-engine aircraft is 100 octane Low Lead (100LL) . It is important to note that jet fuel and gasoline are two completely different fuels for two completely different uses.