Using ethanol free gas.

Sport45 wrote:

JaxDad wrote:
BTW, the reason a calorie can't be used in the way you've suggested is that it's temperature dependant. It is the measure of the amount of energy needed to raise a given amount of water by 1 deg. C. and that varies with temperature, whereas a BTU or Joule does not. Cold gasoline contains the same amount of energy as hot gasoline.

Actually Turtle is right. A calorie is a measure of energy. It's not temperature dependent, that's just the standard used to define it.

A calorie us the amount of heat needed to raise 1 gram of water 1 degree Celsius

A Calorie (like you see on a candy bar wrapper) is 1000 calories

A BTU is the amount of heat needed to raise 1 pound of water 1 degree Fahrenheit

Each unit of energy has it's own definition and conversions can be made between them.


As far as the gasoline goes, cold gasoline contains more energy per gallon that hot gasoline. This is because of thermal expansion. The energy per unit mass remains essentially constant. Since you buy gas and diesel by volume (gallons) you are always better off buying in the early morning when the fuel is colder.

At least that used to be the case. Modern pumps may have temperature compensation.