Some of us have installed a ethanol percentage gauge and sensor. This is really not necessary, however.
This is what I did to get started using e85:
1. I purchased the Holley "test tube", followed the directions and tested out the e85 I was planning on using. It turns out that Propel (the e85 I use) was actually e85. This is good to know because it affects your inputs to step 2. Follow the directions, add water, then e85, and shake the test tube. Then read out the percentage of ethanol.
2. I have an Android phone, so I downloaded two programs:
a. e85 mix calculator - This takes care of the math on how many gallons of 91 octane gas and how many gallons of e85 I need to use.
b. Propel app. This lets me know where all the Propel (e85) gas stations are located at.
In my case, the Arco gas and the Propel gas I use are both in Fullerton, CA, and are only 5 blocks apart.
3. You need to have a good idea how much fuel is in your tank. The way I do this is to fill up with 91 octane gas when the miles until empty says 60 or 40 or 30 or 20, and keep track of the number of gallons I needed to add to fill the tank. Subtract this from 12.4 ( number of gallons in a FiST), and you will know how many gallons you have in your tank.
Example: I filled up my ST when I had 28 miles until empty. I used 11.07 gallons, which means I had 12.4 - 11.1 gallon = 1.3 gallons in the tank. 40 Miles until empty usually means I have 2 gallons of gas in the tank.
Then you plug in the numbers into the e85 mix calculator and it tells you how many gallons of gas and how many gallons of e85 to put into your tank.
So, if I have 1 gallon of fuel in the tank, and its 91 octane, this means its 10% ethanol. Propel e85 has 85% ethanol, and my desired E% is 40.
According to the app, I put 6.84 gallons of Arco and 4.56 gallons of e85.
Then the ethanol percentage gauge confirms that I have e40.
The only thing that changes the second fill up is the E% in the tank. It goes up from e10 to e40.
Get the e85 mix calculator program and play with it, and it will become very clear what and how you use it.
https://play.google.com/store/apps/details?id=com.kennethnissel.e85&hl=en
