INTRODUCTION

Henry Fords first vehicles ran on ethanol. To the average consumer, all energy matters are important issues, but, unfortunately , they have been beyond the control of the average citizen. However the average citizen can do many things to conserve energy, in many different areas. A large part of the energy problem can be attributed to our American fixation with the automobile and it’s huge use of finite petroleum resources. Many countries around the world have millions of vehicle running on alcohol today. The idea of using alcohol for fuel is not new but becoming more attractive to the public as our dependence on gasoline becomes increasingly more expensive. In this paper , I will examine and explain

the engine alcohol conversion process.

ALCOHOL FUELS

Not all alcohols are suitable for use in internal combustion engines. Not all can be produced cheaply, and others have too high of a boiling point to be used in an engine. However, there are two alcohols that are greatly suited for use in the engine--METHANOL(CH3OH) and ETHANOL(C2H5OH). Both of these fuels are in common use today. Both fuels are made from sources that are potentially renewable. Methanol is what makes sterno burn in a heater,and is generally mad from wood or coal, and ethanol is

familiar to anyone ever tasting grain alcohol, and is made from almost any biomass, usually corn.

PROBLEMS

Alcohol is more corrosive than gasoline.
Alcohol doesn’t vaporize as easily as gasoline, making cold weather starts more difficult.
Alcohol has less heat content, requiring richer mixtures.

TERMS

Octane Rating=The measurement of the fuels ability to resist pinging, and detonation.
Volatility= The ability of the fuel to vaporize or atomize.
Mixture= The ratio of air to fuel.
Richer Ratio= Higher percentage of fuel to the air.
CARBURETOR MODIFICATIONS
Current carburetor designs were developed specifically for use with gasoline, the amount of fuel needed to be delivered during alcohol operation is much greater. Carburetor modifications necessary to operate the spark engine on different amounts of alcohol fuel are reasonably easy to make. The two types of carburetors in use on small engines are the fixed jet and the variable jet. Carburetors having a variable jet and needle valve to control the fuel to air ratio/mixture are the best to use when experimenting with different fuels. Needle valves are adjusted when the engine is operating. Fixed jet carburetors need many

different jets sizes for the many different changes that take place running on ethanol.

THEORY

The amount of fuel to be metered through he fuel system is complicated and will be determined by the
following factors:

A. The heat value of the fuel
B. The operating economy of the engine
C. The amount of power desired
D. Ambient air temperature and conditions.
E. Engine operating conditions

1. THE HEAT VALUE OF THE FUEL

Alcohol fuels have a lower heat value than gasoline. Gasoline has an approximate value of 125,093
BTU’s / gallon. Ethanol has an approximate value of 76,375 BTU’s / gallon. Considering only the heat
value of ethanol, it is obvious that more fuel must be consumed to produce an equivalent power to
gasoline.

2. OPERATING ECONOMY

From the heat values given earlier, one can calculate that since ethanol has approximately 66% of the
energy of gasoline the fuel flow through the engine will be close to 1.5 times more than gasoline. Jet
sizes need to range from standard to as much as 50% more in size. Because of many other factors such
as improved compression and longer burn times the fuel mileage is not reduced by as much as 50%.

3. POWER LEVELS

Performance will suffer with leaner fuel mixtures. With richer fuel mixtures, however, engine response will be considerably greater than with rich gasoline mixtures. This is due to the much higher latent heat of alcohol, which can produce power increases as much as10% to 15% above gasoline. One has to watch the INDY car races and watch as the drivers richer mixtures for more power and speed, or lean out the

mixture to conserve the fuel.

4. AMBIENT TEMPERATURE CONDITIONS

In today’s modern automobiles with engine feedback and computer systems, the incoming air is measured for temperature, pressure and humidity. The fuel is then metered in accordance with preset guidelines for the correct ratios during all speed and power requirements. On small gas engines without computers and feedback systems, we need to calculate and adjust mixtures by changing jetting for all of the conditions mentioned above. In cold weather operations and engine start up, correct mixture ratios will be much richer due to ethanol’s low volatility and high heat absorption abilities in the engine chambers and fuel passageways. Alcohol does not vaporize as easily as gasoline and mixture distribution tends to be less even and with larger particles of fuel in the mixture. Preheating the fuel, such as running the fuel line over the cylinder head, can be of value. Operation in warm weather

presents fewer problems.

5. OPERATING CONDITIONS

If the engine is going to be running under steady speeds and loads, then the mixture is going to be easier to set for the correct combustion. When the engine speed is changed and the load requirement changes constantly, then the mixture is much more difficult to adjust and get correct. Remember that the ratio changes as engine RPM increases and load requirements change. With the relatively simple carburetors used on small engines, the mixtures will not be correct most of the time, (such as with a computer feedback fuel injected system). This is the time that most of the experimentation comes into use.
Ignition Modifications.
The power duration and timing of the spark needs to be changed Rich fuel mixtures will absorb more heat energy from the spark without reaching burn temperatures. To complicate matters further, ethanol is not as volatile as gasoline and doesn’t vaporize as easily as gasoline. This results in much larger fuel particle size in the combustion chamber prior to firing, also not leaving many particles between the

electrodes during the spark.

1. SPARK PLUGS

The standard spark plug will work, however, increasing or widening the gap, changing the heat range to a hotter running plug, or going to multiple gap plugs will show an increase in performance.

2. IGNITION COILS

Again the stock coil will work. Replacement coils, (super coils), with more power, (wattage), will increase the spark duration, ensuring that more particles of fuel will be ignited.

3. SPARK TIMING

For all small engines the time at which the spark fires across the plug electrodes is set by adjusting the dwell, (point gap), and is not easily adjusted to the correct value. Some engines have adjustable timing, but it is set to fire the spark at the same under all conditions. In larger engines that are always changing speed and load, requirements for different spark timing follows a curve. Vacuum and centrifugal advance mechanisms are used to maximize the ignition timing curve. On modern engines electronic ignition eliminated the need for mechanical point and condensers. Most of the ignition system is all contained in the coil assembly, which is then attached to the engine block. To change the timing on these engines, the coil assembly needs to be rotated on the block, or the flywheel containing the magneto magnet must be advanced with offset keys. Either of these processes are difficult to do. Also remember that the timing is fixed to fire at the same time always. To much advance will make for very difficult starting. (Have you ever had the starter rope pulled out of your hand on a backfire because of too much advance and the piston will run backwards down the cylinder?) Maybe someday we will have small

computer adjusted variable spark timing.

THE ENGINE COMPRESSION RATIO

Most modern automobile engines are advertised as having compression ratios between 8:1 or 9:1. These are about as high as low octane fuels will permit without some detonation. Small gas engines with L Head designs often run much lower ratios such as 6:1 or a little higher. Depending on mixture strength ethanol fuels rate from 90 to 120+ octane, and could stand compression ratios as high as 13: 1 or 14:1. By shaving or milling the cylinder head down several thousandths of an inch, the compression ratio can be raised substantially. The higher the compression ratio is the richer the mixture must be to avoid

destructive detonation or knock.

SUMMARY

Finally there are really only three changes to make on any internal combustion engine using E-85 for the fuel source. The first of these and perhaps the most important is to change the fuel ratio to run a richer mixture, from around 25% to as much as 50%. I have found that by purchasing 6 new stock jets for the fixed jet carburetor used on the supermileage vehicles, then using a tip cleaner for the Oxy-acetylene torch, We have opened up the orifice to many different sizes. I keep them sorted by using 35mm film containers and then labeling them. Secondly , would be to enhance the spark process. There are many different manufactures for the parts necessary, do some research. Third and finally, we increase the compression ratio by shaving off material from the cylinder head thereby reducing the amount of combustion chamber volume. We had to take and carefully remove material from around the spark plug area because of piston interference. Valve to head clearance should also be checked. For more

information on E-85, there are numerous sources on the inter net to check out.

Keith D. Anderson, DTE
763-786-2844
kdanderson8370@comcast.net
Past President MTEA
Competition Committee -MTEA Supermileage