E85 is becoming a more popular and viable option for performance applications, sometimes being referred to as the “poor man’s race fuel”. There are a few precautions one must take when converting, and extracting the most power from it. When converting your vehicle to run strictly on E85 or in conjunction with gasoline as well, there is a list of fuel supply items that every vehicle is required to replace. Many vehicles only require switching the main fuel supply components, while others require a conversion that is more involved. Newer vehicles often require fewer parts to convert, while older vehicles need to replace most ancillary items. We’re going to take a look at some of the basics in this article.
Newer vehicles are typically easier to convert because the EPA requirements for vehicle manufactures changed around the 2000. So older cars or trucks require a more involved approach when converting to E85. David Deatsch, from DeatschWerks, says the “OEs have been utilizing ethanol compatible fuel systems since 2007, so if your car is 2007 or newer, you are in good position for e85 conversion. In addition, the EPA has certified all US vehicles back to 2001 as having ethanol compatible fuel systems.
So what is E85? E85 is exactly what the name states, 85% ethanol and 15% gasoline. E100 is straight ethanol. There is a large misconception that uncontaminated ethanol is corrosive to the fuel system or engine. This is not true, however methanol is, and this may be where the confusion takes place. During the inception of ethanol use, drag racers were treating it like methanol because of its similar alcohol properties. Soon they found ethanol not only burned extremely clean, but it was not corrosive at all.
Naturally ethanol is hygroscopic, so it absorbs water just like your brake fluid does. If the overall volume of E85 is contaminated by 2 percent or more of water, it passes that threshold where organic acids begin to take place. These organic acids, such as formic acid or acetic acid, can adversely affect soft metals like brass, copper, or aluminum. The solution is to keep your E85 water free.
Another precaution is to use E85 compatible fuel components that resist corrosion. There has been documentation regarding aftermarket cotton based fuel pump socks and fuel cell foam breaking down with E85 use. Always check with the fuel pump or tank manufacturer to play it safe. Deatsch says “Even these newer vehicles may contain rubber fuel lines and other components that will break-down over time regardless of the fuel being used. Therefore, regular inspections and maintenance is suggested. For older cars (pre-2001) converting to e85 DeatschWerks recommends replacing all fuel lines and fuel filters as well as, cleaning or replacing the fuel tank.”
Chris Mills at DeatschWerks added, “If someone is converting an older car from gasoline service to E85, it is recommended the lines are thoroughly inspected and consider replacing, as well as, cleaning or replacing the fuel tank. E85 dissolves many of the deposits gasoline leaves behind and vice versa. One of the recommended maintenance routines we suggest to our customers is to run a tank of gasoline through the system once every 4-5 tanks and to never store a car for an extended period of time with E85 in the system.”
Thirsty for E85
When converting to E85, the general rule of thumb is to increase the overall capacity of your current fuel supply by 33 percent. For an EFI system, this typically involves 33 percent larger fuel injectors and a 33 percent larger fuel pump. Again, this is an estimate not exact percentage. Mills also mentioned, “The OEs typically have anywhere from 15-30% headroom built into the flow of the OE components, that’s why someone bolting on basic breather mods and a tune can get away without changing the injectors or pump(s).” His recommendation goes further and he adds, “Beyond just injectors and pump upgrades, I would consider a FlexFuel sensor and the hardware/software necessary to use the FF sensor a must-have for converting to E85.”
Unleaded gasoline’s stoichiometric ratio is 14.7:1, or when lambda is equal to 1, while E85 is about 9.7:1. So for example, if you’re currently running 35 lb/hr injectors with gasoline, you’d need to increase to about 47 lb/hr injectors to run E85. Also remember that you only want to run a maximum of 80 percent IDC (injector duty cycle), so the injectors are atomizing efficiently and emitting a uniform spray pattern, so always take that into account.
After installing larger fuel injectors and pump, the last necessary step is critical. To finish up the conversion the vehicle must be tuned specifically for E85. Some vehicles have an open source ECU, allowing owners to flash the ECU using uploaded or bought software. The other more costly option is, switching to a standalone system like the AEM Infinity, which has flex-fuel sensor capabilities built in. Having a standalone system will allow more flexibility for the E85 tune, and the ability to run flex-fuel sensors which monitor the ethanol content of the fuel.
By incorporating a stand alone ECU with a flex fuel sensor, the ECU has the ability to use a FF sensor to adjust timing advance and air fuel ratio (AFR) automatically dependent on ethanol content. The ability to have a self-adjusting FF stock ECU is still in its primitive stages, but the option is there. With some OEM computers and any stand alone ECUs there is also the option of having a “dual map” programmed by your tuner, giving you the ability to run either unleaded gasoline or E85, with the flick of a switch. Whatever route you decide to take, getting proper tuning and swapping the appropriate parts is essential for an optimized E85 conversion.