Converting Your Car To Run On Alcohol: A Diy Guide

Converting a car to run on alcohol is a complex process that requires careful planning and execution. While it is possible to convert any car to run on pure ethanol, the level of maintenance and the specific type of engine will vary. Older cars, for example, tend to be used for this conversion, as they are not necessary for daily use, and working on their engines may alleviate concerns about how alcohol could adversely affect newer models. Before beginning the conversion, it is crucial to ensure that the car runs reasonably well on gasoline. The conversion process involves several key steps, including modifying the carburetor, intake manifold, and ignition system, as well as installing a cold-starting system and adjusting the main jet, idle jet, and timing. The accelerator pump changes and fuel flow adjustments are also important considerations to ensure the car runs efficiently on alcohol. The cost of the conversion for a do-it-yourselfer is estimated to be between $250 and $300.

Choose a suitable car

Choosing a suitable car to convert to run on alcohol fuel is an important first step in the conversion process. Here are some factors to consider when making your decision:

Type of Car

The type of car you choose is important. Older cars are typically better candidates for conversion to alcohol fuel, as they often have engines and fuel delivery systems that are more compatible with alcohol fuel. Cars with carbureted engines, for example, are more suitable for conversion to ethanol fuel. On the other hand, newer cars with modern fuel injection systems may require more extensive modifications or may not be suitable for conversion at all.

Condition of the Engine

It is crucial to assess the condition of the engine before deciding to convert it to run on alcohol. Ensure that the car runs reasonably well on gasoline first. Address any major engine issues, such as a bad starter, old spark plugs, or cracked spark plug wires, as alcohol fuel will not fix a problematic engine. Converting a car that is already experiencing mechanical issues may further complicate the process and affect performance.

Usage of the Vehicle

Consider whether the car is your primary mode of transportation or a secondary vehicle. Converting a car that you rely on daily may leave you without transportation during the conversion process. Opting for a second car or a vehicle that is not necessary for daily use can provide peace of mind and allow you to work on the conversion without time constraints.

Availability of Parts

Before choosing a car for conversion, research the availability of ethanol-compatible parts. You will need to replace the entire fuel system, including the tank, lines, and carburetor, with components that are safe for ethanol fuel. Ensure that you can source these parts and that they are compatible with your chosen vehicle.

Potential Engine Damage

Be aware that using ethanol fuel in older engines can potentially cause damage over time. Ethanol attracts water vapour, which can lead to rust in steel gas tanks and water contamination issues. It can also dry out rubber components in fuel systems. Consider the age and condition of the car's engine and fuel system, and be prepared to replace or upgrade certain parts to minimise potential damage.

Your Level of Mechanical Expertise

Converting a car to run on alcohol fuel requires a certain level of mechanical knowledge and skill. If you are new to car modifications, consider choosing a vehicle that is simpler to work on or seek guidance from experienced individuals or mechanics. This will help ensure a smoother conversion process and reduce the risk of errors.

Prepare the engine

To prepare the engine for conversion, it is important to ensure that your car is in good condition and running reasonably well on gasoline. Alcohol will not cure a sick engine, so realistic expectations should be set. It is also important to note that pure ethanol is hygroscopic, meaning it attracts water vapour, which can cause steel gas tanks to rust and dry out rubber components in fuel systems. Therefore, it is crucial to assess the compatibility of ethanol with your car's engine and fuel delivery system.

Once you have determined that your car is suitable for conversion, the next step is to drain any remaining gasoline from the fuel line. Start the engine and let it run until the gasoline is depleted. Then, advance the engine to a faster idle, ensuring that it remains smooth. Check the timing by listening for "pinging" during acceleration. If pinging is present, the timing must be retarded, and the correct setting will be just below the point where the pinging disappears. The exact amount of advancement will depend on your specific engine, but a ballpark figure is 24º BTDC (Before Top Dead Center).

Now, let's move on to the carburetor. The carburetor will need to be modified to achieve the correct air/fuel ratio for efficient burning of alcohol. The ideal ratio for alcohol is around 9/1, compared to 14/1 for gasoline. To achieve this, you will need to modify the main jet, which is usually a threaded brass plug with a hole drilled through it, also known as the main jet orifice. The size of this hole directly impacts the richness or leanness of the air/fuel mixture. Since alcohol requires a richer mixture, you will need to increase the size of the hole by 20 to 40%. This can be done using an electric hand drill.

Additionally, you may need to make changes to the accelerator pump, which injects a stream of gas into the carburetor when the accelerator is depressed. Enlarging the orifice by about 20% or adjusting the stroke length of the pump arm will ensure a proper supply of fuel for alcohol combustion. It is also important to consider the choke valve, which restricts airflow when the engine is cold. As alcohol does not vaporize well in cold engines, an automatic choke will be necessary to adjust the airflow as the engine heats up.

Finally, it is crucial to address the potential issues with gaskets when removing the carburetor. Gasket issues can render your engine incapable of running on either alcohol or gasoline. Therefore, it is essential to have spare gaskets or a gasket in a tube for high-temperature use before proceeding with carburetor removal. Once the carburetor is removed, turn it upside down to drain any remaining gasoline from the float bowl. Then, remove the carburetor air horn and locate the main jet, which is usually in the main well support or in front of the float bowl body.

Modify the carburetor

Modifying the carburettor is a crucial step in converting a car to run on alcohol. The carburettor's function is to supply the cylinders with the right amount of fuel and air. For a car to run on alcohol, the carburettor must be adapted to achieve the ideal air-fuel ratio for alcohol, which is around 9:1. The process involves removing, modifying, and replacing the carburettor.

Firstly, it is important to note that removing the carburettor is a complex task that requires prior knowledge and experience. It is essential to have spare gaskets or a gasket in a tube for high-temperature use to avoid engine malfunction. To remove the carburettor, disconnect all hoses, tubes, and paraphernalia, including the air filter housing. Once the carburettor is detached, turn it upside down to drain any remaining gasoline from the float bowl.

The next step is to locate the main jet, which is typically found in the main well support or in front of the float bowl body. The main jet orifice is a hole in the centre of the main metering jet, and its diameter determines the richness or leanness of the air-fuel mixture. Since alcohol demands a richer mixture, the main jet orifice must be enlarged by 20 to 40%. This process requires specific tools, including a screwdriver, wrenches, pliers, and an electric hand drill.

Additionally, adjustments to the accelerator pump may be necessary. Most automotive carburettors have an accelerator pump that injects fuel into the carburettor throat when the accelerator is depressed. To ensure proper functioning with alcohol, the orifice size should be increased by about 20%. Alternatively, the stroke length of the pump arm can be adjusted to achieve the desired fuel injection.

Finally, preheating the carburettor or fuel line is essential for efficient alcohol combustion. Since alcohol struggles to vaporise in a cold engine, applying an external heat source to raise the fuel temperature above 70° F is recommended. A hand choke can also be installed to restrict airflow when the engine is cold, and it can be manually adjusted to allow more air as the engine warms up.

Adjust the accelerator pump

To adjust the accelerator pump, you must first understand its function. The accelerator pump is a mechanically activated plunger or diaphragm that injects a stream of gas directly into the carburetor's throat when the accelerator is suddenly depressed. This action balances the excess air sucked in as the throttle plate opens during acceleration.

The accelerator pump is inactive when the engine is idling or when the accelerator pedal is held in a steady position. The choke valve, located in the air horn above the venturi, restricts airflow into the carburetor when the engine is cold. As the engine heats up, more air is allowed in through the choke valve.

When converting a car to run on alcohol, it is important to adjust the accelerator pump to deliver the correct fuel-to-air mixture. Alcohol burns most efficiently with an air-to-fuel ratio of around 9:1, which is richer than the ratio for gasoline. To achieve this ratio, you may need to enlarge the orifice in the carburetor throat by about 20% to allow for a greater fuel flow. Alternatively, you can adjust the stroke length of the pump arm to pump in more fuel. Always consult the manual for specific instructions.

It is also important to consider the increased fuel consumption that will result from the richer air-to-fuel ratio required by alcohol. Ensure that you install parts that can handle the greater flow volume without compromising engine performance. Additionally, all fuel system components should be ethanol-compatible to prevent corrosion.

Test and refine

Once you've modified the carburetor and completed any necessary fuel line changes, it's time to start up your converted car and test and refine its performance. Here's a step-by-step guide:

Priming the Carburetor:

Prime the carburetor with a few drops of gasoline. This will help prepare the engine for its initial start-up with alcohol.

Filling the Tank and Cranking the Engine:

Fill the alcohol tank with your chosen alcohol fuel, such as ethanol. Crank the engine and let it run to expel any remaining gasoline from the fuel line. Advance the engine until you achieve a faster yet smooth idle.

Checking and Adjusting Timing:

Listen for "pinging" in the engine during acceleration. If you hear this sound, you need to retard the timing. The correct setting will be just below the point where the pinging disappears. Fine-tune the timing by making small adjustments until you're satisfied. The setting will depend on your engine; for reference, the optimum setting for one conversion project was 24º BTDC (Before Top Dead Center).

Warming Up the Engine:

Let the engine warm up, and then set the idle. Slowly back out the idle adjusting screws, turning them a quarter turn at a time, until you achieve a smooth idle. If your engine has two idle screws, ensure you adjust both by the same amount each time.

Test Drive:

Get behind the wheel and test drive your converted car. Pay attention to any unusual symptoms during the drive. Refer to troubleshooting guides or resources to understand and address any issues that arise.

Refinement and Maintenance:

Keep in mind that converting your car to run on alcohol may require ongoing refinement and maintenance. For example, pure ethanol is hygroscopic, attracting water vapour, which can cause steel gas tanks to rust. Ethanol can also dry out rubber components in fuel systems. Regularly inspect your car and address any issues related to using alcohol fuel.

Frequently asked questions