Gas doesn't typically "boil", but it does vaporize (evaporate) at anything over 93 degrees F or so. As I understand it, the "boiling point" of regular 87 unleaded is about 181 degrees...but this will differ depending on pressure and what additives are in the gas. That said, I would be in no hurry to boil gasoline in order to check that number.

 

Altitude will also make a difference in the 'boiling' point of any of the fuels you mentioned.....

 

...which is why Avgas has a higher boiling point.

 

Higher than what? Here is the specs for avgas, not a bad fuel to use on a drag car with at or under 13 to 1.

http://www.eaa.org/autofuel/avgas/avgas_specs.asp

 

At sea level, at atmo pressure it is roughly 160*. Under pressure it's higher, under vac it's lower.

 

Gas is made of a combination of chemicals with different vaporization temps, so it has a vaporization curve. Methanol and E100 ethanol are single chemicals and do have a fixed vaporization point. Below is a link to VP's master fuel table, the far right column has the spec sheets with vaporization curves for their fuels.

http://www.vpracingfuels.com/master-fuels-table

 

I have heard and seen the 93 octane gas in my fuel tank boiling when I drove it in hot summer temperatures. The pump will start cavitating, sounding different, and then you notice the fuel pressure gage dip and the engine quits. Kurt Urban posted he has seen pump gas boil around 140°F.

I had big time problems with hot fuel and pump cavitation during the True Street cruise at LS Fest this past Saturday. I was able to limp back to the track by wrapping a tee shirt soaked with cold water around the fuel pump but it knocked me out of the race.

I plan to work on fuel line routing to reduce proximity to heat sources and then add a voltage controller for the fuel pump.

 

pump gas is good to about 130-140f.