E85 Ethanol
The Idea of E85 is fantastic in my eyes. I am greatly concerned about the dependence on fossil fuels. I am also concerned about the harmful emissions that race cars and production cars produce. Generally race cars do not use catalytic converters (emissions devices) and run with excessive fuel in the high rpm and high load tables (at least than needed more than is generally needed) to cool the combustion process. While this is how things have been done for years and years, It is my belief (along with others, IRL in 2007 (100% ethanol) and possibly NASCAR in the near future) that we should move our emphasis to alternative fuels that provide the power that we are used to but in a somewhat cleaner, more renewable fashion.
This is a hotly contested subject in the Environmental Studies crowd. There have been a number of studies (One in particular from a gentleman named Mark Jacobson, A Stanford University atmospheric scientist) that are contesting the environmental benefit of Ethanol in any form, E10 or E85. He is saying that the presence of E85 in densely populated areas can actually lead to more cancer deaths as a result of the emissions from E85 powered automobiles. I do not personally have the resources or knowledge to contest this statement, although there have been organizations that have fought back against this study (www.e85fuel.com). At this point I do not know who to believe really. It almost seems that everyone has a special interest of some kind with ethanol.
Well cutting the debates out of ethanol makes it seem nicer. I enjoy tuning with ethanol for the following reasons, it’s a high octane fuel (great for giving your self room to play with higher compression / high boost set ups), it is somewhat renewable (even if it is not the most efficient way from corn…), and it’s really cheap! It has recently gone down to $2.54 a gallon at my station in Annapolis, MD.
Getting ahead of my self a little…
You may be asking what is E85?
E85 is a mixture of denatured ethanol and regular gasoline. This mixture is 85% denatured ethanol and 15% gasoline. Denatured Ethanol is pure ethanol (E100) that has 4.73% gasoline mixed in. (Basically 5 gallons of gasoline in a 100 gallon container of ethanol).
The specific energy output of ethanol is quite less than gasoline.
You can make up for this in quantity.
- denatured ethanol energy content (btu) = 77,815 btu/gallon
- gasoline energy content (btu) = 114,132 btu/gallon
There is a simple energy equation that lets you calculate and compare the energy in E85 as compared to gasoline and other fuels.
Denatured Ethanol (77,815 btu/gallon) * .85 (this is 85%) = 66,143 btu/gallon
Gasoline (114,132 btu/gallon) * .15 (this is 15%) = 17,120 btu/gallon
Therefore E85 equals 83,263 btu/gallon.
FYI Here are the btu/gallon ratings of other popular fuels.
Gasoline = 114,132 btu/gallon
Diesel Fuel = 138,000 btu/gallon
Ethanol (pure) = 78,000 btu/gallon
Methanol (pure) = 56,800 btu/gallon
Propane = 84,500 btu/gallon
Compressed Natural Gas = 19,800 btu/gallon
Sander, what does this mean?
Well, you may have noticed the energy output per gallon is quite a bit lower than normal gasoline that you are probably using in your car right now. This can be over come by quantity burned per power stroke. The stoichiometric ratio of gasoline is 14.6:1-14.7:1. This is the ratio of parts of air to one part of fuel. (14.7 parts of air to 1 part of fuel = 14.7:1). This is the relationship to air needed for a complete burn. Most race cars/performance street cars using regular leaded or unleaded pump or race fuel run in the area of 11.5-13.0 depending on type of induction. The illustrate the larger amount of E85 needed for complete combustion, the stoichiometric ratio of E85 is in the area of 9:1 – 10:1. (fewer parts of air to one part of fuel means you need more fuel…) The general idea is that you will need in the area of 20-30% more fuel as compared to pump gasoline.
Now you might be thinking “Dude, I don’t have a wide band air fuel meter that reads down that low?!?” (Or you may not…)
Regardless, many people forget what a wide band air fuel meter does. The sensor for one of those wide band meters does not just sit in your exhaust and give you a number. It measures the oxygen content. Remember OXYGEN CONTENT! The manufacturers who make most wideband air fuel meters (PLX, AEM, FJO, and TechEdge) calculate the oxygen content needed to produce a perfect burn ratio for normal pump GASOLINE. This assumes that the stoichiometric air fuel ratio of the fuel you are using is 14.7:1. What if you use a gasoline calibrated wide band to tune a car that runs methanol? (Stoichiometric ratio of 6:1) If you try to get that gasoline calibrated wideband to read 6:1 your car will not run, start, or be happy, and your oil will begin to stink of alcohol. You must remember what I told you a few lines up. The OXYGEN CONTENT needed to produce “a perfect burn” post combustion is always going to be similar regardless of fuel. So this is when the great “Lambda” comes in to play. Lambda is a Greek symbol that is also used to denote the stoichiometric ratio of any fuel. So the stoichiometric ratio for Methanol is the same as the stoichiometric ratio for gasoline… 1. Lambda of 1 is the same oxygen content regardless of fuel type. So you don’t have to remember all of these different fuel types and their ratios and what you should and should not tune for! All you have to do is remember that you want to be in the ball park of Lambda of .8 or less for high power applications. This is why the higher dollar wide band systems (MoTeC PLM) are all denoted in Lambda.
Ok, so you need a larger quantity of E85 to make it work on a gasoline engine. It is cleaner as you’ve said, is there any other reason why I should switch?
YES! E85 local to me (Annapolis/Baltimore, MD) is in the $2.5x range. I haven’t yet mentioned that E85 is also in the 100-105 octane range, and Ford has netted 5% overall horsepower increases just by switching to E85 in their somewhat popular FFV cars (Flex Fuel Vehicles). So “in theory” you could go up to your pumping station that carries E85 (when your car is tuned for it!) and buy 105 octane gas for the low $3 range. Who wouldn’t love cleaner race gas for $2.5x / Gallon, that has the possibility to give you more power.
I use E85 in my own K20A race car. It has proven it self reliable at the track with over 1200 track miles on this current set up so far. Holding within 10 hp of our fresh dyno tune of 217 wheel horsepower and 161 wheel torque. Below is a demonstration of the power benefit that could be yielded when switching to the fuel.

- Sander