Converting Diesel Engines: Running Smoothly On Alcohol

The transportation industry is a significant contributor to global carbon emissions, with diesel engines being a notable culprit. While electrification is a growing trend, it is not a one-size-fits-all solution, especially for heavy-duty vehicles like trucks. ClearFlame Engine Technologies offers an alternative solution by modifying diesel engines to run on renewable plant-based ethanol, reducing emissions by 45-50%. This article will explore the process of converting diesel engines to run on ethanol or other types of alcohol, including the necessary modifications, benefits, and potential challenges. We will also discuss the history of alcohol fuels and the potential for a greener future in the transportation industry.

Diesel Engine Conversion to Run on Alcohol

Using ethanol or methanol from renewable sources

ClearFlame Engine Technologies is one company that has successfully converted diesel engines to run on ethanol. ClearFlame's mission is to bring rapid and cost-effective decarbonization to sectors that are hard to electrify. They have developed a solution for a diesel engine so that it can operate without the use of diesel fuel and instead utilize decarbonized liquid fuel, like ethanol or methanol that can be made from renewable sources. This reduces greenhouse gas emissions, particulate matter, and smog, helping to improve air quality and mitigate climate change.

BJ Johnson, ClearFlame CEO and co-founder, talks about how the company is enabling heavy-duty and off-highway industries to transition to fossil-free heavy-duty powertrains faster and at a lower cost than any alternative. ClearFlame engines provide a 45-50% reduction in emissions, which is a larger reduction in CO2 than one would get from switching to electrification, because the grid still has carbon intensity.

Ethanol is a renewable fuel made from various plant materials collectively known as "biomass". More than 98% of U.S. gasoline contains ethanol to oxygenate the fuel. Typically, gasoline contains E10 (10% ethanol, 90% gasoline), which reduces air pollution. Ethanol is also available as E85 (or flex fuel), which can be used in flexible fuel vehicles, designed to operate on any blend of gasoline and ethanol up to 83%. Another blend, E15, is approved for use in model year 2001 and newer light-duty vehicles.

To convert a carburetor engine to an ethanol engine, three changes need to be made: the main jet, the idle jet, and the timing. The main metering jet in the carburetor will need to be enlarged by 20 to 40% because alcohol requires a richer air-to-fuel ratio. The idle jet will also need to be adjusted, and the ignition timing will need to be advanced by turning the distributor housing in the opposite direction that the rotor spins. It is also recommended to install a manual choke instead of an automatic choke designed for gas.

Removing the carburetor

To convert a diesel engine to run on alcohol, you must first remove the carburetor. This process involves dealing with gaskets, so it is important to have spare gaskets or a brand of gasket in a tube for high-temperature use.

First, remove the carburetor's air filter housing and all its hoses, tubes, and other attachments from the engine. Once the carburetor is free, turn the unit upside down to drain out any remaining gasoline from the float bowl.

Next, remove the carburetor air horn and locate the main jet. The jet will usually be in the main well support, but it could also be right in front of the float bowl body. The main jet is a threaded brass plug with a hole drilled through the center, which directly affects how rich or lean the air/fuel mixture will be when the engine is running at normal speeds.

To remove the carburetor itself, start by turning off the fuel valve and disconnecting the hose. Loosen the clamps securing the carburetor to the manifold, paying close attention to any hoses, wires, or linkages. Once all of these are detached, carefully remove the carburetor. Drain all excess fuel that remains.

Taking apart the carburetor must be done in the proper order, starting from the bottom with the carburetor float, then the jets, and finally the mix and idle screws. To remove the float bowl, unscrew the four screws on the bottom of the carburetor with care, as they strip very easily. The float bowl can then be pulled off, and the float pin removed with a pair of needle-nose pliers.

The jets are screws with a hole through the center that the fuel flows through to mix with air. They can be removed with a flat-head screwdriver. The main jet is short and fat, while the pilot jet is long and skinny. The air screw and idle screw can also be removed with a flat-head screwdriver and are located on the sides of the carburetor. The idle screw is larger and adjusts the idle when the engine is idling, while the air screw is smaller and adjusts the airflow when the engine is running.

Adjusting the main jet, idle jet, and timing

To convert a carburetor engine to run on ethyl alcohol, three changes need to be made: the main jet, the idle jet, and the timing.

Main Jet

The main metering jet in your carburetor will usually be a threaded brass plug with a hole—known as the main jet orifice—drilled through its centre. The diameter of this hole dictates how rich or lean the air-fuel mixture will be when the engine is running at normal speeds. The smaller the hole, the less fuel will blend with the air, and the leaner the mixture will be. As alcohol requires a richer air-to-fuel ratio, it is necessary to bore out the main jet orifice when using ethanol fuel. The increase will be around 20 to 40%.

Idle Jet

When idling, the idle orifice is the only route of fuel to the engine, so the fuel flow will need to be increased. On some engines, it may be sufficient to loosen the idle mixture screw at the base of the carburetor to allow more fuel through. On other engines, the seat into which the tapered screw extends may need to be enlarged by up to 50%.

Timing

To take advantage of the antiknock qualities that alcohol fuel provides, you'll need to advance the engine's ignition timing. This can be done by turning the distributor housing in the opposite direction that the rotor spins—moving it by about 20 degrees is a good starting point. Advancing the timing decreases the injection delay, while retarding the injection increases the interval. Setting the ideal injection timing is critical to maintaining and improving engine performance.

Installing a manual choke

First, it is important to understand the purpose of a choke valve. The choke valve restricts the amount of air entering the carburetor while the engine is cold. This is necessary because fuel does not vaporize well in a cold engine, and reduced airflow is desirable. Once the engine warms up, the choke valve opens to allow more air to enter.

When converting to an alcohol-based fuel system, it is recommended to install a manual choke rather than an automatic one designed for gasoline engines. Manual choke conversion kits are readily available and affordable.

To install the manual choke, you will need to access the carburetor. This involves removing the air filter housing and disconnecting all hoses, tubes, and associated components. Once the carburetor is exposed, turn the unit upside down to drain any remaining gasoline from the float bowl.

Next, locate the carburetor air horn, which is typically found in the main well support or directly in front of the float bowl body. The choke valve is positioned above the venturi in the air horn. At this point, you can install the manual choke valve, ensuring it functions smoothly and seals effectively.

By following these steps, you will successfully install a manual choke as part of your diesel engine's conversion to run on alcohol. Remember to refer to the conversion kit instructions and seek expert advice if needed.

Converting to an ethanol-based engine

Converting a diesel engine to run on ethanol is a viable option for those looking to reduce their carbon footprint and transition to fossil-free energy. ClearFlame Engine Technologies offers a solution for diesel engines to operate without diesel fuel, using decarbonized liquid fuel like ethanol or methanol.

ClearFlame's technology is based on the principle that any substance can burn if it's hot enough. Their solution involves making the fuel injection system compatible with a different fuel, in this case, ethanol. Alcohols have lower lubricity, which results in a higher flow rate.

Conversion Process

The conversion process for a gasoline engine to an ethanol-based engine involves several key changes:

• Main Jet Changes: The main metering jet in the carburetor needs adjustment. Since ethanol requires a richer air-to-fuel ratio, the main jet orifice must be enlarged by 20-40%.
• Idle Jet Changes: Adjustments to the idle jet are necessary for optimal performance.
• Timing: To take advantage of the antiknock qualities of alcohol fuel, the engine's ignition timing must be advanced by turning the distributor housing opposite to the rotor's spin direction.
• Choke Alteration: Installing a manual choke is preferable to an automatic choke designed for gas.
• Accelerator Pump Changes: Almost all carburetors use an accelerator pump, which injects a stream of gas into the carburetor when the accelerator is depressed. To accommodate ethanol, the orifice must be enlarged by about 20%.

Benefits of Ethanol

Ethanol, or distilled alcohol, has been used as an alternative fuel since the early days of the Ford Model T and is still compatible with many modern engines. It offers several benefits:

• Reduced Emissions: Ethanol reduces greenhouse gas emissions, particulate matter, and smog, improving air quality and mitigating climate change.
• Flexibility in Meeting Climate Goals: Ethanol provides a pathway to net carbon zero, offering flexibility in how we meet future climate goals.
• Reduced Carbon Output: Diesel engines contribute significantly to carbon emissions, and converting to ethanol can drastically reduce soot and smog, leading to cleaner-burning engines.
• Energy Security: Our reliance on oil makes us vulnerable to supply disruptions, which can cause economic recessions. Ethanol provides an alternative, reducing our dependence on crude oil.
• Cost-Effective Decarbonization: ClearFlame's solution offers rapid and cost-effective decarbonization for sectors that are challenging to electrify, such as heavy-duty industries.

Dual-Fuel Option

Another option is to convert diesel engines to run as dual-fuel engines, using a combination of diesel and ethanol. This method can improve thermal efficiency and provide significant advantages in reducing greenhouse gas emissions. Additionally, using ignition-improving additives can ensure compression ignition without requiring changes to the fuel supply system.

Frequently asked questions