Getting Good Quality E85

February 21, 2024
Getting Good Quality E85

Whether you have a flex fuel 5.7 Hemi Ram or an e85 tune Mustang GT, you want to get the most from your e85 fuel. But what constitutes quality e85 and where do you find it?


The first thing you need to know is that ethanol is ethanol. Because ethanol is corn alcohol, there is no difference in the ethanol component from one fuel to another. But e85 is a mixture of ethanol and gasoline, so the gas component is the variable. 


Sadly, because ethanol is very knock resistant, your local gas station can order e85 which is a mix of ethanol and low-octane gasoline that would not be suitable for their gas pumps. This can result in some pretty poor performance and run characteristics. When we talk about junk E85, what we are generally talking about is the quality of the gasoline in the mix. 


The other question in terms of good or bad E85 is content. By federal standard, the e85 you get at your local pump has to be between 51 and 83% ethanol. No matter what your five-dollar tester from Summit says, you will never get 85% ethanol at any pump unless it is a separate race grade pump at a Sunoco station or at the track. The standard E85 is going to give you something short of 85%. 


Although 50% ethanol will give you the equivalent knock resistance of 105 octane gas, in dyno testing we see the best gains in terms of horsepower and torque with at least 78% ethanol in the tank, so you want to get the highest content you can find.


Our FlexLink virtual ethanol gauge and our Commander flex fuel management systems all link to our ProFlex Connect app and allow you to see real content in real time. You can use the FlexLink in any car, even ones with an e85 tune or a flex tune. The app will also search for e85 stations in your area, so you can find and navigate to flex fuel pumps and compare fuels.


When you find a station that has a higher ethanol content, stick with it. They are usually pretty consistent, but not always. Especially in colder climates, the percentages will drop in the winter because ethanol is a little temperamental at start-up in cold weather. Don’t panic if you take your 5.7 Hemi flex fuel car to a Michigan e85 pump in January and find 51% ethanol in the fuel. When the weather warms up, they will go back to a summer mix.


The top shelf for e85 products are race-grade e85 fuels from great names like Sunoco, makers of Sunoco e85R, our high-grade flex fuel of choice. You can also get race-grade E85 from companies like Ignite and VP. When you buy a jug or barrel of race-grade E85, you are getting a guarantee of 85% ethanol content and high-quality gasoline in the mix. Race-grade E85 is more expensive and is generally reserved for track days, but it will definitely provide the best bang, if not the lowest buck.


So, whether you have a fully adaptive ProFlex Commander flex fuel system, a flex tune, or an e85 tune, you want to get the best e85 possible. Look for high-ethanol-content fuels from trusted fuel brands and pay attention to how your car runs, especially at low rpms. When you find a good source, stay with it, and for track days or dedicated race cars, consider investing in a race-grade E85 product like Sunoco E85R.


Now get out there and burn some corn.