E85 Best Practices

Sunday, March 7, 2010 - 9:50am

E85 is becoming more and more the fuel of choice amongst our customers. At DeatschWerks, we receive calls everyday about ethanol compatibility and what size is needed for E85 use.


With the recent release of our 1,000 cc/min EVO X and Subaru injectors, we see E85 utilization doing nothing other than increasing in popularity.

Its easy to understand why people want to switch to a readily available fuel with the octane rating of race fuel at the cost of regular unleaded. Not to mention the environmental benefits. However, the conversion of gasoline powered engines to E85 is not without its pitfalls, that is why we are kicking off our tech-blog series with a “Best Practices” guide to E85 conversion.

  1. Get Compatible. Our new line of 1,000cc injectors are made with ethanol friendly components. This is also true of our universal 1,600cc low impedance injectors. However, having compatible injectors is only part of the equation. Your entire fuel system from top to bottom needs to be evaluated for ethanol compatibility.
  2. Size Does Matter. E85 will require about 30% more fuel than regular gasoline to achieve the same power levels. For example, where a 550cc injector would normally be appropriate, you will need a 700cc injector for E85.
  3. The E85 Quality Quotient. There are considerable quality variations from manufacturer to manufacturer and from station to station. E85 is a blended fuel (85% ethanol, 15% gasoline). When poor quality gasoline is used for blending, a tar-like sludge can build up in your fuel system (particularly on the injector nozzle). This tar-like sludge can also be attributed to improper storage, improper transfer, and water contamination of otherwise good quality E85.
  4. Maintenance = Reliability. Sludge build up is not easily predicted. DeatschWerks, as well as many of the tuners and shops we work with, suggest removing and inspecting your injector nozzles on a regular basis. Also, the sludge is soluble in gasoline so keeping a gasoline map and running a tank of unleaded thru your fuel system once every 1,000-2,000 miles is a good preventative measure. Also, changing your fuel filter on a more regular basis and checking your lines for signs of breakdown is also recommended.
  5. Seasonality Shift. One last important note is that pumps labeled E85 are not always 85% ethanol. Why? Ethanol does not atomize and ignite as easily as gasoline, especially in cold weather. So it is common practice for manufacturers to decrease the ethanol concentration down to 75% or even 70% in the winter time. It is important to take this into consideration when tuning on E85. Many people will make separate maps for the different blends or make one map that is tolerant of the seasonal swing in E85 blends.