Thermodynamic efficiency matters. And detonation is highly efficient, because it's an (almost) combustion isochoric process. The shockwave/detonation front trav

Thermodynamic efficiency matters. And detonation is highly efficient, because it's an (almost) combustion isochoric process. The shockwave/detonation front travels at far higher speeds than the movement/speed-of-sound in both the unburnt input mix, as well as the combustion products. My understanding is that it's due to the combustion performing all it's work before any work/energy is extracted from the hot combustion products. This results in a higher peak temperature, and the higher the temperature difference, the higher the theoretical efficiency limit of converting the thermal energy into mechanical (or equivalent) energy. It's why diesel engines have a lower fuel consumption than gasoline engines: they burn hotter.