Enter your Total Fuel Needed, Target Ethanol Content, and details about your E85 and Regular Gas (ethanol content, octane, price) to find exactly how much of each fuel to mix — the E85 Calculator returns your E85 Needed, Regular Gas Needed, Blend Octane, and Total Fill-up Cost.
E85 Needed
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Regular Gas Needed
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Blend Octane Rating
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Total Fill-up Cost
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Effective Cost per Gallon
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E85 is a fuel blend containing 85% ethanol and 15% gasoline. It offers higher octane ratings (105+) compared to regular gas, allowing for more aggressive tuning and potentially more power in flex-fuel or modified vehicles.
Only flex-fuel vehicles (FFV) or properly modified cars can safely use E85. Regular vehicles require fuel system modifications including compatible fuel lines, injectors, and engine tuning to handle ethanol blends.
E85 ethanol content varies seasonally and by region, typically ranging from 70-85%. Winter blends may have lower ethanol content for cold-weather starting, while summer blends are closer to 85%.
Use your tuner's specified ethanol percentage (like E30 or E50). Enter this as your target content, along with your fuel amounts and the actual ethanol content of available fuels to get precise mixing ratios.
E85 is typically cheaper per gallon but provides 15-25% lower fuel economy. The cost effectiveness depends on the price difference and your vehicle's efficiency on ethanol blends.
Ethanol blends increase octane ratings significantly. E30 typically provides 91-93 octane, while E50 can reach 95-98 octane, depending on the base gasoline octane rating.
For optimal performance and engine safety, aim for within 2-3% of your target ethanol content. Most modern engine management systems can adapt to small variations in ethanol content.