Change in E85 Ethanol Content due to Evaporation

[2ndAmend]

Noticed the E content changing upwards after sitting in the tank a week. Did a quick experiment today. We all know about this but I was surprised at how quickly it happens.

Put some E85 that tested E68 in a cup this morning, figured I’d leave it overnight and test. After about 4hr, it looked like so much evaporated that I might not have enough to test now!

Turned out, I had just enough with a few drops to spare. It tested E81!!! Not what I expected!

 

[CPO Super stock]

I would have thought the E would have evaporated faster!

 

[2ndAmend]

I would have thought the E would have evaporated faster!

The low vapor pressure is why 'E85" is not available in northern climates including NH, ME or VT. I have to drive an hour into MA unarmed to get it!!!

 

[Speedy!]

That's interesting. Kinda how alcohol and water chemically bond and 1 gallon of water and 1 gallon of ETOH doesn't equal 2 gallons of liquid.