Just in case anyone is tempted to play with acetylene, like the guy in the video clip, a few words of warning. Acetylene has the disconcerting property of exploding with extreme violence if the absolute pressure of the gas exceeds about 29 psi. (200 kPa) i.e. gauge pressure 15 psig (101 kPa). No other substance need be present for an explosion; oxygen is not required. Liquified Acetylene is even more dangerous; it is shock-sensitive and liable to explode violently. In the past there were many fatalities at factories making the stuff. There is also another, and more subtle danger. If acetylene is contact with copper, (e.g. a copper pipe) it forms copper acetylide, which is a heat and shock-sensitive explosive when dry. When it goes off it naturally explodes the rest of the acetylene in the system, even if it has not been compressed. Incidentally, acetylene often contains traces of phosphine or arsine, which are horribly poisonous.
It certainly didn't seem like a viable fuel and it appeared to be exploding at other times than when the spark plug fired. Difficult to tell though, due to the amount of soot created. The alcohol didn't seem to vaporise or burn properly at all. Do alcohol burning motors use higher compression normally?? I've an idea they do... Is phosphine what Sadaam used on the Kurds... ??
The guy did not use the more obvious options of ethanol or methanol, both of which are good fuels for engines and can tolerate high compression ratios, but Isopropyl alcohol. No explanation why - maybe he just happened to have some on hand.
I think he chose something that was at hand and readily available on a domestic level. Fascinating to see the processes at work and in slow motion. Had to use a side valve for this of course but it did seem to illustrate the inefficiency of a side valve layout and also, how infrequent the power strokes seem to be on a four-stroke when you're actually watching them happen.
