News & Info

E-85, The race fuel of the future!

As we get more and more involved with E85 and FlexFuel builds, we are more and more surprised at the results we get every day. There is little about this fuel that can be considered bad and even the myths that are being repeated on the web are being disproven. When we are able to achieve nearly 50 to 100 HP gains with fuel alone, there is not much more convincing we need.

Thank you to the IGOTASTi community for much of the following information.

What is E85 and what is needed to run it

E85 is an alcohol and fuel mixture that contains up to 85% denatured ethanol and gasoline. The ethanol is derived from corn or other sugar rich plants which earns it the nick name "corn juice." Because this fuel is comprised of mostly alcohol it has a great effect on performance. Another advantage is its environmental friendliness. It is a cleaner burning fuel and has a much smaller carbon footprint than straight gasoline alone because it is burning carbon that is already in the environment and not carbon that has been locked away millions of years ago as with gasoline. Emissions out of the tail pipe can be considered "Near Zero" in many cases.

To run E85 requires upgrading parts of the fuel system due to the greater amount of volume required to use it. Depending on the turbo size this can range from upgrading just the injectors and fuel pump to a $2,000+ fuel system consisting of huge injectors, multiple fuel pumps, upgraded fuel rails, ect (for a large turbo and power applications). It is best to contact your tuner when determining the necessary fuel system upgrades for your build.

Effects on fuel systems

For the most part, vehicles made from the late eighties and early nineties where designed with oxygenated fuels in mind because of the introduction of E10. Most vehicles nowadays use silicone and/or synthetic rubber seals which are good for ethanol use. The supposed issue here is that it dries out natural rubber and attacks some plastics. Teflon, Silicone and synthetic rubber are good materials to use. We have yet to run into a single issue regarding corrosion of any kind or the drying of any seals. We have been running E85 for several years now in other platforms and did nothing special to the fuel system other than injectors and fuel pump in many cases.

The one thing that I have observed is there is an increase in moisture inside the motor over time and can correlate to corrosion or sludge build-up. With the right counter measures, you can avoid it. For example, on my personal car I have observed the start of sludge build up in the blow by system. By adding Catch Cans, the moisture accumulates in those now and the rest of the blow by system is clear and clean. I emptied 1 cup of clear water from the catch cans after only a couple weeks of using E85 in colder weather but in hot weather this is significantly less. Use of an Air-Oil Separator is not recommended with E85 because you do not want condensed water returning to the crank case.

Chemically, ethanol is really no more corrosive than petroleum, meaning it's not. It is a solvent and not an acid plus the oxygen atoms in its molecule don't become interesting until the molecule is disassociated during the combustion process and that is long after the point that corrosion becomes an issue. The problem with it is that it has a high affinity for moisture and can absorb quite a bit of water. It is the moisture that is causing issues with corrosion and even vehicles designed for it are showing signs of deterioration. I guess one way to counter this is to know your source. If they have a high turnaround of E85 it will not be sitting around long enough for it to accumulate moisture and become stale because ethanol is highly hydroscopic in nature.

Some things that I have employed to counter the effects of moisture and thereby corrosion is...

- Know your source. Find a station with high turnaround
- Catch cans
- Alternate from E85 to 93, I do one tank of 93 to every three tanks of E85.
- Block Heater to prevent condensation and help with cold climate start-up.
- Frequent Oil Changes.

Effects on Performance

It is strange to say that E85 produces more effective power than Gasoline when it has less energy per volume than straight gasoline, but I will attempt to explain how we can achieve more power from a fuel with less energy.

First, let’s discuss the energy contained in each fuel. Gasoline has a stored potential energy of roughly 114,000 BTU per gallon. E85 has a stored potential of roughly 81,800 BTU per gallon. This means we need to use about 30% more E85 to equate to the same energy potential of gasoline. To do this we increase our fuel injector size and adjust scaling to pump about 30% more fuel into the engine. This pretty much closes the gap regarding potential energy from one fuel to the other but there is more to it. See Item 3 below.

Power advantages and effects of using E85 over Gasoline.

1.) The most prevalent benefit is that E85 has a significantly higher octane than gasoline sold at the pump. This allows your tuner to tune aggressively in regards to AFR, timing and boost. For example when tuning boost on a 93 map, one would usually need to dial back the timing to compensate for knock. With E85, one can tune aggressively for boost and maintain the same timing level, or even increase them more. It is realistic to have no knock at boost levels exceeding 30psi coupled with an efficient turbo and still maintain high timing values. However this doesn't mean that we can just up the timing throughout the load/rpm range and call it a tune. The MBT timing for E85 is about the same as gas throughout most of the load/rpm range but can be a bit more advanced in the mid and higher regions of the map. The best way to tune for this is on a dyno.

2.) Also the alcohol in E85 has a HUGE cooling property associated with it as well for both the charge temperatures and exhaust temperatures. It has the effect of keeping cylinder and exhaust gas temperatures low do to the fact that there is so much more volume of fuel being applied. For cooling the air charge, E85 has similar cooling properties you find with Water Meth injection. A cooler charge = a denser charge. A denser charge = more Air/Fuel. More Air/Fuel = more power.

The cooling effect comes when the fuel is mixed with the incoming charge due to the evaporative relationship between the fuel and the air charge and with the relationship between the dry-bulb temperature and wet-bulb temperature of the medium. The farther apart these two numbers are the more cooling effect occurs. Evaporative cooling is a property in which evaporation of a liquid into surrounding air cools an object or a fluid in contact with it. You might be thinking that the cooling effect can't be better than meth because the mixing of fuel and charge is so close to the combustion. This is not so much the case for two good reasons...

- The first is because the evaporation rate of Ethanol is significantly greater than the evaporation rate of Methanol and can cool the charge at a much greater rate. The cooling phenomenon is felt more with ethanol even though it has a short path to travel. These evaporative properties are greatly increased due to the air velocity and turbulence at the intake valve. When the charge transfers from the low volume chamber in the head to the high volume chamber of the cylinder, the cooling effect is amplified. The only time this point is moot is when you are using direct injection to deliver fuel. In that case there is no travel time for fuel to mix with the air charge and for evaporation to occur.

- When meth is injected, its cooling effects begin immediately but are reduced as the charge absorbs heat energy along the intake path.

3.) There is a fair increase in exhaust load and energy output because you are increasing the amount of thermal energy per pound of air consumed and though a specific volume of E85 has less energy than the same volume of gasoline, we are increasing the fuel volume by 30% when using E85. That, combined with the air charge... you can see by the math below that the energy output of the intake charge, consisting of fuel combined with air, is greater than gasoline...

Thermal energy of Gas = 19,000 BTU/lb
Thermal energy of E85 = 13,475 BTU/lb

Let’s assume a consumption of air @ 100lbs/hr

100lbs/hr / 14.7 AFR = 6.802 lbs/hr of gasoline @ 19,000 BTU/lb = 129,238 BTU @ Lambda of 1
100lbs/hr / 9.76 AFR = 10.246 lbs/hr of E85 @ 13,475 BTU/lb = 138,065 BTU @ Lambda of 1

So you can see that the final thermal energy output is greater even though E85 has less energy per volume due to the fact that we are using more of it per pound of air. Ultimately this will increase the cylinder pressure thereby increasing the exhaust load affecting the potential for quicker spool and greater torque.

Conclusion

E85 has far reaching advantages with little risk or cost so it is our go-to fuel for both race and street application at the same time being environmentally responsible.