corn Alchohol and the MG mg logo

Alcohol, Alcohol, Alcohol

Methanol and ethanol are two varieties of alcohol that have been used as alternative fuels for gasoline powered internal combustion engines. I am not a chemist nor a thermo dynamics engineer, but I will present some useful real world information relating to the use of these fuels in our beloved MG’s.

Both methanol and ethanol are chemically characterized as weak acids - keep this in mind. The chemical descriptions of each are: methanol- CH3OH; ethanol- CH3CH2OH. Methanol is synthesized from the methane present in natural gas while ethanol is distilled from fermenting vegetable starches such as corn, barley and wheat. Both alcohols are readily miscible with water - not only do they mix with water they actually attract it - keep this in mind.

Methanol is corrosive to aluminum, magnesium and zinc, and the presence of brass serves as a catalyst which speeds up the process. Ethanol is most corrosive to ferrous metals - those metals which contain iron, such as steel. This corrosion leaves behind salt deposits and a jelly like substance, both of which can clog filter screens (such as in some SU fuel pumps and SU carburetor float lids) and fuel filters.

In today’s market, methanol has been discarded as a viable alternative partly due to the cost of production. Ethanol however is receiving much attention due to its “renewable” resource classification and latest studies claim that it has a ratio of energy yield to cost of production yield as high as 1.6 to 1. Comparing ethanol to gasoline in the energy output arena is interesting. On a volume basis ethanol has about 66% of the BTU capacity as does gasoline - keep this in mind also.

Current production vehicles from Detroit (or wherever) that are designed to run on ethanol blends are called Flex Fuel Vehicles(FFV). Ford has always been proud of their FFVs - you may have noticed a small symbol on such vehicles characterized by two small green leaves and sometimes the words “Flex Fuel” on the same logo. These (and other manufacturers as well) vehicles have specially designed fuel systems to accommodate alcohol blend fuels. This includes plastic fuel tanks, plastic and/or stainless steel fuel lines and fittings, alcohol tolerant fuel injectors and fuel pumps and a sensor to detect the presence and concentration level of alcohol in the fuel. Keep this in mind…

So what does this mean to us? The use of ethanol blend fuels in older vehicles can and will be problematic. I don’t know about your MG, but our MG’s certainly have a glorious combination of materials in the fuel system - steel fuel tank and lines; fuel pump and carbs with brass, aluminum and zinc components. Will the corrosive nature of alcohol be a problem? Absolutely. How ‘dry’ is the fuel system in your MG? Moisture is in the air we breathe and so is also in contact with the inside of the fuel tank and carb float chambers. Temperature fluctuations (as in evening to morning) cause condensation. Collected condensation forms water droplets. Water droplets collect and sink to the bottom of fuel tanks and float chambers. Your lawn is not the only place dew occurs! Now, what is in the bottom of a fuel tank and float chamber? The fuel pickup tube resides in the lowest part of the tank, and the float chamber fuel outlet is in the bottom of the float chamber. Small amounts of water do little besides cause corrosion. Larger amounts are drawn into the engine where an immediate and unfavorable change in engine performance is noticed. You may think that your MG has been drinking! Okay, so now let’s throw in some good old Indiana liquid corn…

The ethanol will mix hold onto the water and allow it to mix with the gas - which is a good thing, sort of. This will prevent the water from rusting a large hole in the fuel tank. However, now the gasoline’s volume is partially displaced with alcohol and water. Remember that 66% BTU capacity figure? Now we have a fuel blend of gasoline, alcohol and water. A larger volume of this fuel is required to provide good engine performance. If the percentage of water is too high, engine performance falters - hesitation, stumbling, backfiring and other abnormalities quickly get your attention. The bottom line is this: if it wasn’t designed to run on ethanol, don’t expect it to do so.

Many fuel suppliers already supply gasoline with a limited amount of ethanol –look closely at the pump next time you fill up any car. The pumps are required to be labeled regarding alcohol content. You might ask the attendant, if there is one, but I have found they usually don’y know or care. Typically, 10% is the most you may encounter in this area. And generally, most cars will tolerate this - assuming the fuel system is clean and in good repair. If you do notice a performance problem after ingesting some of this fuel, carburetor enrichment will help. On H and HS type SU’s the jet adjustment nuts can be turned DOWN one half to one turn (three to six flats on the nut). On HIF style carbs turn the mixture screw IN one half to one turn. On Stromberg carbs use the proper needle adjusting tool and turn it IN one quarter to three quarters of a turn. Note: these figures are approximate and may require some tweaking to put the MG back into good sorts.

The best advice is to:

  1. Keep the fuel tank closer to full than empty. You do not save money buy purchasing gas $10 at a time-you are inviting trouble! This minimizes the amount of air in the tank which will contain moisture. Remember, our older car fuel systems are NOT sealed as tightly as a newer car.
  2. Change fuel filters at least bi-annually. Clean fuel screens in pump and carbs at the same time.
  3. Buy a good brand of fuel. Contrary to popular belief, gas is not gas. And who knows what happens to it between the refiner, the jobber and the dealer?
  4. Don’t tempt fate. Stay away from high alcohol fuels, and DON’T buy E85 fuel for the MG. This is 85%ethanol, 15% gas; intended for the Flex Fuel cars. Yes, alcohol is here, and probably to stay. Federal mandates are in place to see to this. But political regimes are just that-political, and subject to change.
  5. When storing the MG for the winter fill the fuel tank, add a bottle of “Stabil” or “Sea Foam”, drive the car for for a half hour, THEN park it. Note: This is not the complete procedure for winter storage - just what the fuel system needs.

What is the long range outlook? Good question. I don’t personally see the extinction of gasoline. Newer alternative technologies are emerging all the time. I believe the oil companies will keep this cash cow around as long as possible. New alternatives may arise to replace gasoline that will be old technology friendly - I hope.

Areas for further information: The United States Department of Energy, Alternative Fuels web site: