Watch this. When he uses the Alcohol it doesn't vaporize the fuel properly but only converts some of it to gas that burns and pushes the piston down. Look at the difference between that and the gas he uses.
Look at when he runs the Spirytus which is Polish Vodka. The Chamber is saturated but some of the mixture gets vaporized so it still burns and pushes the piston down. That mixture would be very rich AFR wise but only a little bit of it actually gets burned to produce power. There's quantity and then there's quality of mixture, 2 very different things. What do you think happens in a low comp engine with a big cam? You may give it 12.8 to 1 AFR but it doesn't mean your engine uses all of it.
Listen to sound and the differences between the gasses and the liquids