That's okay Sunder, and no, this is from me, not copied from some other source. <img src="/forums/images/graemlins/lol.gif" alt="" /> Just a poorly educated chemist attempting to understand and discuss openly my limited knowledge.
I think that gasous acetone or even wood alchol would combust at different pressure/temperature than gasoline causing multiple "explosions" or combustions, even in a homogeneous gaseous mixture. I'm not sure, though. The fact that if too much heptane is used in the gasoline blend, knocking, or multiple combustions, will be more pronounced/noticeable. Possibly, the gaseous homogeneous mixture would combust at one pressure/temperature? The point about gasoline being a blend, and the more octane, C8H18 molecules, type fuel used in the blend, the less knocking, or multiple combustions will occur, I'm pretty sure is correct. Knocking is a term that is used to discuss multiple combustions in the engine's cylinders. That's my limited understanding. I believe it, combustion, is explosions, the pressure/temperature rapidly releases the energy held in the molecular bonds. Burning fuels is a violent release of the chemical energy stored in the chemical bonds that hold the organic molecules together. The energy is released as light, sound, heat, . . .
Octane is a molecule, you're confusing it with the octane rating system; a gasoline of 100% octane (C8H18) has a rating of 100%. Airplane fuels usually have an octane rating of 120% (different blend). anti-knock additives work the opposite of a catalyst, ie., negative catalyst. Rather than promote sites for combustion to take place, negative catalysts inhibit sites for combustion to take place.
If you haven't noticed, I ain't putting acetone in my vehicles . . . I'm not a proponent of this, I simply brought it to the board because I thought it was interesting! <img src="/forums/images/graemlins/cheers.gif" alt="" />