This article is for informational and educational purposes only! I take no responsibility for any damages or injuries sustained as a result of a person's actions based on the information in this article.
At the request of EagleMark, I wrote this article to provide some in-depth information on the various aspects of converting a vehicle to run on E85 and other ethanol blends. I have assembled a comprehensive list of information that is relevant to the use of ethanol as a fuel.
A couple terms requiring defining/clarification;
For those that are unfamiliar with E85 or alcohol fuels. The term E85 refers to an increasingly popular and increasingly available fuel that is comprised of 70-85% ethanol and the remaining portion being gasoline and/or other chemicals commonly added to gasoline. Although the term E85 indicates 85% ethanol, the ethanol content will vary between 70-85% due to factors that I will discuss in further detail later. Ethanol is ethyl-alcohol and as such is commonly simply referred to as alcohol. The importance of clarifying the term alcohol as it is used in this article is because there are 3 completely different types of alcohol commonly used by and/or available to the average person. The 3 commonly seen types of alcohol are; 1. ethyl-alcohol (ethanol, grain-alcohol, "drinking" alcohol, etc...) 2. methyl-alcohol (methanol, wood-alcohol, etc...) 3. isopropyl-alcohol (rubbing-alcohol, etc...). Also, just about anything that can be said about E85 applies to pure ethanol and vise versa. The major differences from gasoline will obviously be greater with pure ethanol vs. E85 and I can elaborate on the specifics if needed. That being said, for the purpose of saving time and avoiding confusion, I will try to avoid hopping back and forth between the terms E85 and ethanol except when necessary.
The vehicles I have converted;
I have successfully converted 3 personal vehicles (2 TBI Firebirds and 1 MPFI Nissan 240sx) to run on E85 over the last 4 years accumulating well over a combined 100k miles with the most being on my current Firebird which I ran on E85 up until I removed the original 305 at ~212k miles (still running too I might add).
The Nissan was my first project, and other than chipping the ECU, I made zero modifications to the engine or fuel system to make the conversion. It was a 1990 Nissan 240sx equipped with a 2.4 liter inline 4-cylinder engine and MPFI induction. The compression ratio of these engines is a very modest 8.5:1 which is pretty low by today's standards especially for an engine equipped with aluminum cylinder head(s). Both of the Firebirds I converted are '89 Formulas equipped with TBI 305ci engines. These engines have a slightly better compression ratio of 9.3:1, but it is still relatively low. The significance of compression ratio when using ethanol based fuels will be addressed later. The first Firebird I converted had zero modifications as well and did ok. But, with an old TBI fuel pump and typical fuel pressure running the stock TBI fuel injectors it did lean out in the upper RPM range at WOT. The second Firebird got a walbro 255lph high pressure fuel pump which was way overkill and resulted in an inability to maintain a steady operating fuel pressure lower than 21psi. A fuel pump upgrade for a GM TBI system would be considered necessary for just about any type of modification that would result in an increase in fuel flow and/or pressure. However, the particular pump I used is not suited for this type of fuel system. I should have removed it and replaced it with a milder fuel pump, but anyone who has installed a fuel pump in a 3rd or 4th generation F-body would understand my reluctance to remove the pump. A small bump in fuel pressure and fresh TBI style fuel pump would be all that the stock engine would need to keep up with fuel demand. An O.E. multi-port style fuel pump is also acceptable and will also allow for more engine upgrades later.
The use of E85 in these vehicles has not had a negative impact on them at all from what I have observed. I have never experienced any fuel system problems whatsoever such as the hoses and seals deteriorating or the metal components corroding. I have also not experienced any other mechanical issues that could be linked to E85.
I have experienced longer cranking times in the winter and also "carburetor-like" driveability issues until the engine reached operating temperature. All 3 vehicles took longer to warm up in the winter and subsequently it took longer for the heat to be effective. The cold-weather issues were more pronounced with the Firebirds due to them having TBI which is a wet manifold setup. My current Firebird would never fully warm up or produce much heat when I left a 160 degree thermostat installed during the winter. I would have to change to a minimum of a 180 degree thermostat in the winter to have sufficient heat when running E85. I also found it to be better if I let the cars warm up for a bit before driving due to the cold driveability issues with E85. The use of E85 in cold weather can be a bit of a turn off for some people. Cold engines do not start or run well on E85 once the ambient temps drop below the 40's and will take longer to reach operating temperature as well. Once an engine has reached operating temperature it will behave normally though. An engine with port style fuel injection will not have as many cold weather issues, but they are still apparent. Some of the cold weather issues can be lessened by good tuning, but they cannot be completely eliminated without additional modifications. Modifications such as an engine heater or starting the engine on gasoline then switching to E85 are effective and have been used, but are only worth the additional cost and work if the vehicle is used in more extreme cold climates.
The impact on fuel economy vs. the price difference of E85 would pretty much cancel each other out currently. Depending on your reasons for wanting to use E85 that could be seen as either a good or a bad thing. My reasons for running E85 were for research, performance, and somewhat environmental so I am relatively indifferent. It is possible for E85 to be cheaper, but there are many factors keeping the prices high at the moment.
Lastly, all 3 vehicles just plain ran better on E85. They all idled smoother and experienced a small but noticeable increase in torque and throttle response. One could argue that this was more psychological than anything else. But, aside from that being a well-known and documented attribute of running E85, I did change back and forth between gas and E85 several times and the performance difference was both noticeable and consistent. For reasons that will become more apparent later in this article it is important to note that when running gasoline I always use premium grade in all of my personal vehicles. The differences would be more pronounced for someone that typically uses regular or mid-grade gas.
Overall, I have had mostly positive results from running my vehicles on E85. I am also looking forward to getting the bugs worked out of the current engine and fuel system in my firebird as I will go right back to running E85 once that happens.
The physical properties and characteristics of ethanol vs. gas;
The stoich ratio for 100% ethanol would be around 9:1 air:fuel with 100% gasoline being 14.7:1 air:fuel. E85 requires around 9.8:1 air:fuel, which is roughly 50% more fuel. The short and simple reason is that ethanol contains less chemical energy than gas. This equates into reduced fuel economy, but actual fuel consumption is not increased by 50% due to many factors that are about to be addressed. Also, good tuning and a good engine setup can close the gap even further. It is important to note that E85 is less expensive than regular unleaded. Although fuel economy wih E85 is lower that doesn't directly equate into higher fuel costs due to price differences and actual fuel consumption.
Ethanol is denser than gas which comes into play with the actual fuel injector flow rates and also atomization. The higher density actually affects the fuel injector flow-rate requirement for a given setup. In plain terms that simply means that although the stoich ratio for E85 requires 50% more fuel you do not necessarily need a fuel injector that is rated at a 50% higher flow rate when "converting" to E85. I THINK that the density also equates into higher difficulty to obtain good atomization or something along those lines.
Ethanol burns more completely and efficiently than gas which is one reason it is added to most of the pump gas found these days and also a characteristic that can be capitalized on. I will circle back around to more specifics on the addition of ethanol to pump gas later. The more complete and efficient combustion of ethanol also equates into a more efficient engine and is another reason that real-world fuel economy will be better than the calculated difference.
Ethanol also burns much cooler than gas does and this characteristic can be beneficial in a couple ways as well as be capitalized on. The lower combustion temperatures of ethanol are easily noticeable on a converted engine. Other than during cold weather operation, the lower operating temps are ususally a desireable trait.
E85 doesn't leave behind near as much carbon buildup in the engine and exhaust as gasoline does (technically 100% ethanol should leave zero carbon deposits behind as the major byproducts of complete combustion of ethanol are water and carbon dioxide).
Ethanol has a higher vapor point and flash point than gas. This means that it is somewhat safer than gas. The higher vapor and flash points are why ethanol does not like cold weather. This is the reason for the actual ethanol content of E85 to be less than 85% sometimes. In the U.S. most companies will lower the ethanol content of E85 to 70% in the winter to reduce starting and driveability issues due to cold temperatures. The higher vapor point of ethanol leads to a cooling effect on the intake charge. Engines with a wet manifold setup will experience a more drastic change with ethanol, but even port injected engines will still experience the cooling effect somewhat. The cooling effect that ethanol has on the intake charge is another benefit and is also another reason that the effective octane rating of E85 is generally higher than the measured octane rating.
Ethanol does not ignite as easily as gas which is actually beneficial. The measurement of the relative ease/difficulty to ignite a fuel is basically the same concept as octane ratings. The effective octane rating of E85 is much higher than premium pump gas (premium unleaded usually has a 92-95 octane depending on the gas company). It is difficult to place an exact number on the octane rating of E85 due to the characteristics of ethanol that will affect the real world resistance to preignition. The gas and chemicals that make up the other 15-30% of E85 also affects the real world octane equivalent, but the common number I see is around 105. It is important to note that the measured octane rating and the effective octane rating will be different with E85 due to it's properties. This is another property that can be capitalized on. An engine specifically designed to run on E85 or higher concentrations of ethanol can be built with a much higher static compression ratio. The higher compression ratio increases thermal efficiency and the end result is more power output.
The burn rate of ethanol is also slower than gas so it requires more ignition advance than gasoline. The ignition timing curve is a key factor in tuning an engine for optimal performance and efficiency.
Engines running on ethanol behave differently and have different fuel enrichment needs when placed under a load. An engine running on ethanol does not require as much enrichment under loads. When under part-throttle loads, an engine running on ethanol does not require as much enrichment. This characteristic will vary based on a specific engine configuration, but is apparent regardless.
Ethanol is hygroscopic, meaning that it readily absorbs moisture from it's surroundings and thus makes it mildly corrosive. However, this also means that the moisture that does make it's way into a fuel system will mix with E85 instead of settle out and freeze in cold temps like it would with regular gasoline. The corosive effects of ethanol have little impact on most automotive fuel systems due to several factors. One reason is simply because automotive fuel systems are constantly exposed to moisture anyway. Another reason, at least with more modern vehicles, is because fuel systems contain a higher amount of plastics and stainless steel that aren't affected by moisture. The significance of this characteristic as it relates to using ethanol as a fuel is that you should not store it or a vehicle containing it for long periods of time.
The fuel vapors that naturally accumulate in the crankcase will not readily mix with the engine oil when running ethanol or E85 as will gasoline. This is a relatively good property as gasoline contamination of the engine oil happens in all engines at varying degrees depending on a few factors. As gasoline mixes with engine oil it has a two-fold effect on the oil that negatively impacts the engine. First, gas will cause the oil and it's additives to break down faster and require the oil to be changed sooner. Second, the gas will thin the oil lessening it's lubricating properties leading to accelerated wear. Gasoline contaminated oil is a major cause of premature engine component failure and leads to a lot of the mechanical failures commonly seen in engines. Because ethanol will not readily mix with oil, this leads to less oil contamination. The only downside to this is that an engine must be operated long enough and often enough for the vapors to naturally evaporate out of the crankcase. The failure to do this will lead to an accumulation of enough vapor condensation to settle in the oil pan. Before I go any further, this scenario is very unlikely to happen to most vehicles as running the engine at operating temperature and driving the car a few minutes is all it takes to properly burn off the condensation. The drag racers that I know of that run straight ethanol will actually have to drain the condensation out of the oil pan occasionally by removing the drain plug and waiting until oil begins to come out. Since ethanol and water are denser than oil, when such accumulation occurs it will settle to the bottom of the oil pan after sitting long enough. The problem is that if this happens, you face the same issues as having an internal coolant leak in the crankcase where the oil and water/ethanol will get whipped up into a milky substance that will destroy the engine very quickly.
Ethanol WILL attack natural rubbers and deteriorate them quickly. However, during the 1980's, automobile manufacturers began using synthetic rubber in fuel systems in order to be compatible with the many different substances that were being added to gasoline. I have read that if you have a vehicle built in the 1980's that is fuel injected it most likely has a fuel system that is compatible with ethanol. In both of my firebirds, I didn't replace any hoses or seals and had no issues. If you have an older vehicle or are in doubt, you can find fuel hoses labeled "fuel injection hose" that are compatible with ethanol at just about any local parts store. It is my understanding that the regular hose available nowadays is compatible with ethanol as well. I strongly suggest using fuel injection hose with ANY fuel injection system including lower pressure systems, like TBI injection, due to it's durability and excellent burst strength.
Ethanol has no lubricating properties like gasoline does. Gasoline has some minor lubricating properties that help protect fuel system components and the top end of the engine. Ethanol does not have these properties and could lead to accelerated wear in these areas. Since ethanol has been a popular fuel in racing for decades, lubricant additives are readily available and don't cost much. However, I have read from various sources that the amount of gasoline and additives present in E85 is sufficient enough to not require any additional lubricant in the fuel. If pure ethanol is ever used, it is recommended to add a lubricant to avoid accelerated wear.
So what does all this mean and how does it apply to converting a car to run on E85 ? In simple terms, for those that are capable of tuning electronic fuel injection (or carburetors too actually) and performing relatively minor mechanical repairs, there isn't much work or cost involved with converting to E85. As with anything, E85 has it's drawbacks and isn't right for everyone. But, E85 has some nice attributes that make it a popular fuel for those with performance in mind and also those interested in environmental issues. Most fuel injected vehicles can be converted with little or no fuel system upgrades to accomodate the increased fuel demand. The exact fuel system requirements will vary based on application, but if you have a fuel system that is in good working order and properly matches the engine's fuel demands currently then the same applies as well. Just about any engine in good working order will experience these benefits when converted to run on E85; they will idle smoother and run smoother, they will run cooler, they will accumulate very little carbon deposits throughout the engine and exhaust, and they will have a small increase in power and throttle response. Generally speaking, an engine optimized to run on E85 can and will acheive more power output than when run on pump gas. The performance characteristics of E85 are comparable to high octane racing fuel in many ways. The lower cost and higher availability of E85 compared to racing fuel make it a popular choice for many low-budget racers and those that take their car to the track occasionally. Because of the lower cost and better availability, E85 is also extremely popular with those that run forced induction. It's properties allow for higher boost pressures and substantially increased power output without increased danger of piston and/or ring damage on a given setup.
As for my advice, this is what I recommend;
When planning for a switch to E85, be sure that your fuel system is up to the task of delivering ~50% more fuel just to keep a safety margin there. Be prepared to stop at the gas station more often as you're definitely going to empty the tank quicker. Make sure that there are enough gas stations that sell E85 near your regularly traveled routes. I also recommend carrying a chip or other way to allow the engine to run on gas just in case you ever find yourself in need of fuel and there is no E85 available. The average increase in fuel consumption when converting from gasoline is generally 20-30% for a standard engine without performing any mechanical engine modifications. The difference in fuel economy can be lowered substantially with precise tuning and building an engine specifically designed to run on E85. Be prepared to spend at least as much time tuning the fuel and ignition tables as you would with any other modification. Expect to experience a few issues with start up and warm up in the winter. For a "starter" tune, increase the fuel constant in the ECM about 30% and add about 5 degrees of ignition advance across the board. It is very easy to get an engine running on E85 and a "blind tune" usually will run better than expected. However, do not be fooled by those facts as it will take a lot of time and experimentation to realize the full potential of E85 as well as acheiving maximum fuel economy. Tuning the ignition timing for the best overall performance and efficiency is tricky. This is because a typical stock N/A engine will most likely not experience detonation regardless of how much ignition advance you add. The obvious best method to tune anything would be with a dyno. This is more important when using an alternative fuel like E85 where there are many more unknown variables. But, with trial and error and the aid of data logging and affordable performance measuring devices, the optimal timing curve can be obtained. If you have any doubt about your fuel lines and seals then replace them as I stated before. Any replacement o-rings for a fuel injection system should be synthetic and just fine. The proper hose is readily available and affordable as previously mentioned. And finally, be prepared to become addicted. I have met nobody to date that has experimented with E85 for performance reasons and not become a fanatic. It seems that alcohol is just as addictive as a fuel as it is as a beverage lol.
That pretty much sums things up regarding the basics. I have much more to add and will do so fairly soon hopefully so stay tuned. I anticipate that I may get swarmed with questions, but I have a very busy schedule so be patient and I will gladly answer questions as quickly as I can.