One thing you could do is get a thermos and set up a stand to place the sausage on inside the thermos. Then, place a container full of a known amount of water on top of an open end of the thermos such that it covers it. Make sure you have a thermometer in the water. Then, ignite the weener and see how much the temperature of the water changes. Now it takes a calorie (NOT food Calorie, see the difference?) to heat one gram of water by one degree Celsius. So we can use the equation, calorie = grams water X change in temp. in Celsius, or for food Calories, Calorie = kilograms water X Change in temp. Celsius.