Bio-Energy Series: Converting Gasoline Engines to Ethanol
by Randy Price and Ed Brokesh
Introduction:
Alternative fuels are becoming more important as gas prices rise and petroleum
resources dwindle. This resource is especially important to farmers who drive many miles
between fields, parts stores, and town. Although many farm vehicles are diesel (and you
should be looking at bio-diesel for those), quite a few farmers still have gasoline vehicles
(cars, trucks, tractors) and you are left with the option of what to do with these vehicles?
If you are lucky enough to be at the end of your automobiles or trucks economic
depreciation cycle, and you are considering buying a new car or truck, then it is very
likely you will find and be able to purchase a FFV (or flex fuel vehicle) that is equipped
to run on any alcohol based fuel up to E85 (fuel with 85% ethanol1, the E number stands
for ethanol and the next two digits after that indicate the percentage of alcohol in the
fuel). If not, you are left with the option of either buying a new car before you are ready,
or burning higher cost fossil fuels. Still, there are some options arriving on the market
that may help you out. These options are conversion kits that allow you to convert your
car to E85. These kits may even be useable on gasoline powered tractors and other
engines with the correct modifications.
Getting the Correct Fuel Ratio Mixture:
The main factor in converting a regular spark ignition fossil fuel engine into flex
fuel engine is to get the fuel mixture correct. Ethanol contains roughly 30% less BTU’s
than regular fuel and requires more fuel to be injected into the engine to get the right
stoichiometric conditions. Stoichiometric ratio is the proper ratio of the air to fuel ratio to
cause complete combustion. A normal car will run this mixture slightly rich to get the
best mileage with least amount of engine wear (an engine running above this ratio will
overheat and ruin the internal combustion parts). The correct stoichiometric ratio for
regular unleaded gasoline is 14.7:1, while 9.7:1 for E85 (and can be any value in-between
for different alcohol/fuel ratios). In newer cars, this means either holding the injectors
open longer to get extra fuel into the engine, or running a higher flow rate injector. In
carbureted engines, this means re-jetting for a higher flow rates. Newer flex fuel cars are
already designed for these large changes in flow conditions and can automatically re-jet
for the various fuel/alcohol ratios (they usually use the exhaust O2 sensor and various
other sensors to determine the correct fuel to air ratio mixture). In older cars (even ones
with injection systems as late as last year), the computer box and injectors cannot hold
the injectors open long enough to get a rich this mixture with the E85 fuel. In Brazil and
other countries, this problem has been circumvented by using a special box that plugs inbetween the computer and the injectors, and causes the injectors to be held open longer
(Figure 2). You could also install a larger set of injectors, but then the vehicle might not
run correctly if you have to go back to regular fuel.
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Ethanol is alcohol based fuel made by the fermentation of corn starch, sugars, and other resources. This is
the predominant alcohol fuel used today and mixed with regular fossil fuel gasoline (although other
versions exist such as methanol, butanol, etc.).
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Engine Components with E85:
Another concern with running E85 is to make sure all the fuel system components
can tolerate the alcohol fuel. Alcohol is a strong cleaning agent and has the ability to
degrade certain engine parts, such as natural rubber, plastics, and even metals, over time.
A list of material affect by E85 can be found at the Alternate Fuels and Advanced Data
Base Center - http://www.eere.energy.gov/afdc/e85toolkit/specs.html.
Current Car Fuel Systems:
Currently, all cars dating back from around 1994 (and most cars as far back as
1985/86) have fuel systems that can handle alcohol fuels. At that time, alcohol was
considered as a replacement for MTBE (methyl tertiary-butyl ether), an additive to used
to raise the octane level and oxygenate fuels for complete burning, and most
manufacturers were required to sell vehicles that could operate with alcohol. Still, some
care must be taken to make sure all the fuel system and components are rated for alcohol
fuels (this even means that the fuel tank and other areas where fuel may contact – lines,
hoses, injectors, etc. – must be considered). The main concern is natural rubber parts
which must be replaced with synthetic rubber parts (luckily most hoses sold today at the
local parts dealer are synthetic!) and the fuel tank should not be made of aluminum.
Metal tanks, although safe for alcohol may corrode and leak from the cleaning action of
the alcohol fuel and need to be replaced. If the tank is metal, you should either clean the
tank by having it vatted at a local machine shop (to insure that there are no leaks), buy a
new plastic tank, or get the inside coated with an alcohol tolerant coating. Another
concern is that many of the impurities (carbon, gum, dirt, etc.) which cause the brownish
tint on tanks and other parts will dissolved in alcohol and be cleaned off ending up in
either the fuel filter or the injectors (which causes clogging – several people have
reported this!).
Gas Mileage on E85:
In any E85 conversion you can expect to lose from a 2 to 30% in mileage (since
alcohol fuels have less BTU’s than regular petroleum gasoline), but many FFV (flex fuel
vehicles) are only losing about 2 to 10%. Note Figure 1 where a Flex Fuel car was
operated with E85 and only saw a 5% reduction mileage. In fact, for this car, more
mileage was lost due to driving speed and habit than the E85 itself (at 78 MPH the car got
26 MPG and at 60 MPH it got 33 MPG yielding a 25% increase in mileage!).
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2008 Chevy Impala Mileage Test using E85 and
Regular Pump Gas (87 Octane)
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33
Mileage (MPG)
32
31
30
29
28
27
26
25
58
60
62
64
66
68
70
72
74
76
78
80
Speed (MPH)
E85
Pump Gas (87 Octane)
Figure 1: Car mileage on pump gas (87 octane regular unleaded) and E85.
Raising the Compression Level:
If mileage and power are a concern, there are ways to get it back. The octane
rating of ethanol is much higher than gasoline and typical resides in the 100 to 105 range.
For this reason, the compression ratio of an engine can be raised without fear of
detonation (a symptom where multiple flame fronts appear during ignition and the
collisions cause high mechanical stresses on engine parts). Before ethanol, most engines
ran an 8:1 compression ratio but today’s engines are running to 10:1 compression ratios.
On ethanol this ratio could be increased to 12:5 to 14:1. This property may lend itself
well to a super or turbo charged engine, where the compression can be raised by merely
changing a pulley or impeller speed to cause a higher boost ratio. Another method is to
mill-the-head, lowering it closer to the piston and reducing the clearance volume but this
requires major engine modifications and may preclude the engine from running on
regular unleaded fuels.
Current U.S. Ethanol Conversion Kits:
In the U.S., a conversion box (Figure 2: plug in-between the injectors) is currently
not allowed because law states that fuel systems cannot be modified from the original
manufacturers specifications. Also, they must undergo strict emission testing to get a
certificate for use on public highways and current fuel injector changing systems are sold
as off-road use systems only. Still, there is one system has been certified for use on
certain cars in the U.S. on public highways. This is the Flex Fuel U.S. system which uses
a bolt-on injector plate (like a nitrous oxide or throttle body injection system) and adds
supplemental fuel through an separate injector plate located before the intake manifold.
This system also contains an alcohol sensor to tell the flex fuel’s computer what ratio of
alcohol you have in the tank and then make adjustments. Since the system does not
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change the OEM fuel system, the system is considered an accessory bolt-on and doesn’t
change the original manufacturer’s fuel system. EPA testing (to get certification also)
with the units has indicated that exhaust gases meet, and in most cases greatly exceed
original manufacturer’s ratings (which is usually the case when you switch from burning
regular fuels to alcohol). The system may also be useable on older carbureted gasoline
engines (even such as those found on tractors and other agricultural engines) since the
system adds fuel through a separate injector plate and can be added easily to a carburetor
system. In this case, a separate fuel injector fuel pump (rated for fuel injection pressures
which is much higher than normal carbureted engines – see Figure 3), supply line, and
return line are installed on the tank to run the flex fuel system. An injector installed
between the carburetor and manifold supplies extra fuel. No other modifications are
necessary. Even the original jetting of the carburetor is left the same. The only caution is
to make sure all the fuel system components (carburetor, fuel lines, fittings, tank, etc.) are
E85 compliant. If the engine is run on regular gasoline, the flex fuel system will turn
itself off and regular gasoline fuels can be run through the engine as normal.
Running an Engine too Lean:
As with the addition of any system, detrimental engine damage can occur if the
engine is run too lean (which causes burning of piston tops, valves, and overheating of
the engine). If you are worried about this, you can install a secondary O2 sensor and
meter to indicate the mixture ratio in the engine available at most parts stores (order a
wide-band O2 sensor to accurately be able to record changes in an engine – most engines
are equipped with a narrow band O2 sensors that are harder to evaluate for mixture
changes). Also, an exhaust temperature gage can be used to indicate extra lean conditions
by noting the rapid rise of exhaust temperatures from normal running conditions.
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Figure 2: Typical Injector PWM Systems.
Figure 3: Typical inline fuel pump.
Cold Weather Starting:
In colder climates, starting may be a concerned when using E85. Alcohol contains
much less explosion potential and has a lower heating point than regular gasoline, which
prevents it from exploding well in a sub-freezing engine. Potential solutions to this are
block and radiator heaters, running regular fuels during this time, starter fluid, raising the
compression of the engine (to aid in explosion), or having a separate fuel tank with
regular gas (and a switching valve).
Licensed Professional:
If you decide to convert a gasoline engine to ethanol, consult a licensed
professional who can help you decide on the changes you need, or a licensed mechanic
who can do the modifications for you. These people will know exactly what parts need to
be changed, and problems that might occur in your situation.
Check List:
The following factors should be considered before attempting to convert an engine
over to ethanol:
-
Can the fuel system support alcohols?
o Are the rubber components alcohol friendly?
o Is the tank made out of a material that can support alcohol?
 Get a metal tank cleaned and possibly coated
 You may need to switch to a plastic tank
 Most new cars have plastic tanks that will work and can be
acquired a junk yards, etc.
o Can the rest of the system support alcohol?
-
Can I regulate the fuel to produce a rich enough mixture?
o Buy an ethanol conversion system for your vehicle.
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Resources:
Alternative Fuels and Advanced Fuel Resources Center:
http://www.eere.energy.gov/afdc/e85toolkit/specs.html
Abcesso Technology
http://www.abcesso.com/index.html?lang=en-us&target=d2.html
Brazil:
Abcesso Exp/Imp. Ltda
Av. Alfredo Baltazar da Silvera 580
Recreio dos Bandeirantes, loja 271
22790-710 RJ - Rio de Janeiro
Brasil
Tel: + 55 21 3521-7216
Skype: abcesso
Fuel Flex International, LLC
Ph: 866-568-3617
Flex Fuel U.S.:
http://flexfuelus.com/
FLEX FUEL U.S.
5820 N. Northwest Highway
Chicago, IL. 60631
Ph: 773 / 763 - 7900
Fax: 773 / 763 – 0878
Rochester Products
http://www.flexiblefuelconversions.com/
250 Mill Street
Rochester, NY 14614
Ph: 585-777-4030
White Lighting: Ethanol Conversion Systems:
http://www.mye85kit.com/
White Lightning LLC
2941 Main Street; Suite F
Santa Monica, California 90405
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