E85 Ethanol In a Non Flex Fuel Vehicle – Pros, Cons, Concerns

Mike McGinnis

E85 fuel is an ethanol gasoline blend which offers performance advantages at drastically lower cost than race fuel. This attractive combination has taken the performance industry by storm. There are many articles about its basic properties. Rather than rehashing that, I’ll focus on key information regarding implementing E85 fuel in a non flex fuel vehicle which we find customers often aren’t aware of. I will cover critical pitfalls and how to avoid them.

In 2007 E85 became available at a tiny gas station in Guelph, Ontario, about 1.5 hours drive from my shop in Buffalo, NY. It was rather inconvenient, but I could see that E85 was going to become popular and wanted to run a bunch of tests on my car before tuning customers for it. The results were fantastic and the vehicle was very fast for its day. Since then, I’ve only grown more fond of E85. That said, there are cons and I make sure people know what they’re getting into.

As I see it, the main cons of E85 are:
-Cost of implementation

Fuel from the first station I used varied wildly in ethanol content so I had to retune the car after each fill. Unlike a flex fuel vehicle which has an onboard ethanol content sensor and engine management calibration that dynamically adjusts tuning parameters, I had a non flex fuel vehicle. When the fuel changed, the tuning didn’t and the engine ran poorly until I retuned it.

Fortunately, stations soon started opening in my city. This was not only more convenient, their fuel was more consistent. This has remained the case. Fuel tests consistently around 85% ethanol, usually from May through October, but we get class 1, 2, 3, and 4 E85 in our region which are blends varying in concentration. Those living in a warmer climate may see less or no variation if winter blends aren’t necessary.

Despite reasonable consistency of the fuel, here are some concerns you should remember:
-The E85 standard does not require stations to maintain consistency. They can alter the blend as they please, usually from 60-90% ethanol content.
-Accidents happen. A couple customers reported they pumped regular E10 gas from an E85 pump because whoever filled the station’s tank made a mistake.
-When you switch back and forth between fuels, draining or pumping out the tank rarely gets all the fuel out.

For these reasons, everyone running E85 should have a wideband air/fuel sensor and ethanol content sensor they can monitor. Being aware of ethanol content and air/fuel changes is the first step. Making the appropriate adjustments is the key. When tuning a non flex fuel vehicle, I generally make customers engine calibrations for E10 gas, E15, E30, E60, E75, E85 or thereabouts depending on the situation. These approximate mixtures have been chosen based on experience with resulting mixtures when a car is switched from gas to E85 or from E85 back to gas. Many vehicles have side saddle tanks with a single in tank pump in one saddle. If you drain one saddle via a plug or by pumping the fuel out, the other saddle can still have gallons of fuel in it. When draining gas and filling with E85 ethanol, achieving E60 is common. When draining E85 and filling with E10 gas, E30 is common. After driving and using up that tank of fuel, the next time you fill up the mixture changes again until you’ve worked the other fuel out of the system entirely. This often takes about 3 full tanks of fuel, so it’s important to have engine mappings for in between mixtures.

Some non flex fuel vehicles adapt to changes in ethanol content indirectly via closed loop fuel trimming based on oxygen sensor readings referenced against air/fuel ratio targets. Most modern vehicles do this, but the quality and range of response varies wildly from platform to platform. Some vehicles with onboard high quality wideband sensors/controllers and newer engine management system will trim fueling 25% in fractions of a second to achieve targets despite changes in ethanol content. Some trim fuel under light load conditions such as idle and cruise, while others trim fuel at all RPM/loads as long as some other criteria are met i.e. engine temperature is within a certain range and sensor warmup is complete. I find it’s best to rely on this as little as possible. Know your ethanol content via a sensor/meter, load an engine mapping appropriate for that ethanol content, then monitor your air fuel readings to confirm you are on target. This way little to no trimming is required. Drivability, efficiency and safety are all improved. The less you rely on reactive systems and the better you proactively load an appropriate engine calibration, the better off you’ll be.

In terms of implementation, most setups require at least one upgraded fuel pump and upgraded injectors, potentially multiple pumps, lines, rails etc. for higher HP setups. Install a good wideband air/fuel meter (if not already equipped) and ethanol content sensor/meter. It also doesn’t hurt to have a graduated cylinder style ethanol content tester as well so you can test before filling your tank. Many modern fuel systems can tolerate E85, but some cannot. Talk to your builder/tuner about potential vehicle specific concerns. Also keep in mind ethanol is rather hygroscopic. While ethanol may not harm your fuel system, water likely will. Even if you have fuel system parts that are noted E85 safe, avoid E85 being left in the tank for extended periods of time. I also suggest running vehicles fueled with E85 at least once a week to reduce the risk of corrosion of fuel injectors and other components.

In our area, running E85 during the warm months and switching to gas for the cold months often makes sense. This avoids pumping mystery fuel, improves cold engine start and allows the engine to warm up quicker. If you don’t live in a cold climate that may not seem a big deal, but around here nobody wants to wait longer than they have to for their vehicle to provide heat in the cabin. Also keep in mind if it gets cold enough, your engine will not start normally or at all on E85. Having an emergency can of starting fluid just in case is recommended. Summer blend E85 generally doesn’t start well below 50 F, though I’ve tuned some cars on summer blend fuel that did start around 30 degrees F. Winter blend E65 generally doesn’t start well below 10 degrees F, and perhaps not at all below 0 degrees F, but this varies with setup.

If the reality of using pump E85 in a non flex fuel vehicle hasn’t scared you off, you’re ready to enjoy the benefits and they can be huge. Just like with great race gas, horsepower and torque gains of 20, 50, 100 or even more are possible with the proper supporting modifications and engine tuning. If you’re more concerned with increasing margin of safety against detonation than adding power, you can do both with E85. If you want to reduce intake, combustion and exhaust gas temperatures, E85’s latent heat of vaporization doesn’t match methanol, but does offer greater cooling than gasoline. I’ve given you a lot to think about so let it stew, talk to your builder and tuner, and you make the call if E85 is right for you.