E85 Don’t Do It! Unless you know…
"What you're doing and the pros and cons of burning this in your vehicle."
What is E85?
E85 is a fuel blend. A blend that holds ~85% ethanol and ~15% gasoline.
Ethanol is basically a bio-fuel since it’s obtained from biomass sources such as corn crops, grains and “starchy” wastes in the US or sugarcane, wheat and sorbent in Brazil and Australia…
While regular fuel blends have an octane reading varying from 87 to 94… fuel and ethanol blends ranging from E10, E20, E30, E40 to E85 have octane readings between 89 to 105.
Should I run E85?
To lure you in, the quick perks to E85 are:
– price per gallon is smaller than other blends
– it can create more torque and HP
– adds a cooling effect to engines because it’s an alcohol type-fuel
However not everything is fine and dandy because E85 comes with some real drawbacks too. Let’s list off a few:
- Not all cars can run ethanol type fuels safely – Older vehicles (prior to 2008 and any vehicle not specifically built to burn high ethanol blends) are taken out of the equation from the beginning. Ethanol has a corrosive action on fuel-system components, magnesium, aluminium and rubber. Running E85 on an older model engine without tuning it and replacing some components will ruin the engine in short time. Replacing fuel hoses, fuel pumps, gaskets, seals, fuel filters, fuel injectors, throttle bodies, etc. and other components besides tuning your fuel system, can easily run the bill up since you need to change so many components to properly run E85 fuel blends.
There are recent models that have been designed to work with ethanol-gas mixtures up to a certain point or FFV (Flex Fuel Vehicle) that can run with any blend up to E85, but still use caution unless your vehicle warranty specifically states that you’re covered in the event of damage related to E85.
- E85 fuels are hygroscopic – That translates into a short storage and tank life because its prone to absorb moisture from the air. It also means that depending on how long the gas stays in your tank or the humidity level of your geographic area, you can experience poor performance and even problems with fuel injectors.
- It’s susceptible for pre-ignition – Due to its ethanol component, it’s more likely to ignite before the piston compresses and the spark plug does its job.
All it takes is an impulse such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events. This doesn’t sound like something all that bad, but it certainly is. Pre-ignition means that the fuel sprayed into the cylinder ignites before it should thus creating an unbalance in the engine internals and putting stress on components. This leads to engine knock where the combustion process doesn’t happen at the optimum time for a four-stroke cycle. The shock wave creates the characteristic metallic “pinging” sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive as I can personally attest to.
- Lower MPG – Because it’s a blend of alcohol and gasoline, a typical car burns 20-30% more quantity to match the figures that regular gasoline pumps out. That translates into 20-30% fuel consumption increase over the same number of miles vs regular gasoline. E85 is usually cheaper than regular gas but sometimes not as much to compensate the increase in consumption. Sometimes you might end up paying more in gas for the same trip… and in more ways than one if your vehicle is not designed and engineered to burn E85.
- Components lifespan reduction and cold weather – Running ethanol based fuels in Fuel Flex Vehicles is fine since they are specifically designed to withstand all the effects ethanol blends come with. Some people can’t afford a newer FFV vehicle, or simply just want to keep their current one and possibly modify it to run with E85. Due to its corrosive nature and as we mentioned here before… E85 affects fuel system components, magnesium, aluminium, rubber hoses, gaskets and paper fuel filters. Another important detail to factor in is that the fuel pump usually has gas flowing around the pump and motor mechanism that lubricates it. This is not the case of E85 fuels, because they lack this important lubrication component.The electric fuel pump can fail sooner than normal due to this lack of lubrication plus the fact that it’s working harder to pump 20-30% more fuel for the same travel distance. Cold weather is an important aspect to take into consideration because engines running on E85 fuels tend to start a little harder and take some time to idle before you can drive it properly. Not letting it idle usually results in a very poor performing engine and also high emissions until it gets to operating temperature. Couple this with the lack of lubricity E85 offers and you’re in for some additional challenges. Cold weather brings humidity up and E85 fuels are very receptive to this. They tend to attract this extra moisture and you will most likely end up with water in your gas tank that participates in rust formation and also can choke your engine if you’re running on carbs or even damage your fuel injectors.
- offer your engine the lubricity it needs (and lacks when running E85, although again… not recommended in non FFV’s)
- eliminate carbon deposits which can become hot spots that trigger pre-ignition
- remove harmful water condensate
- eliminate slagging and cold-end corrosion
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About the Author
Passionate about Jeeps, mechanics and all the new ways to improve engine performance.