Car Repair and Maintenance

How to Modify Your Car to Run on Alcohol Fuel

It feels strange that you can modify your car to run on alcohol fuel. Truthfully, alcohol can be your fuel source in the absence of gas. You will no longer experience a gas shortage, join the queue at the pump or get to pay higher fuel prices. Some farm tractor makers still produce alcohol engines. However, they are export only, so you do not get to see them around.

How to modify your car to run on alcohol fuel

Looking at the current state of international politics, you can see that imported crude oil is affected and the cost is always on the rise. With alcohol, you no longer have to rely on crude oil to power your vehicle. Apart from consuming alcohol during an event, it can also relieve the pain of refilling gas.

Meanwhile, nearly all gasoline-powered engines can run on alcohol as fuel and you require just minor and inexpensive engine modifications to get started. If you have decent mechanical skills alongside the hand tools, this engine modification would be even easier.

What Are the Different Types of Alcohol Fuel?

Some centuries ago, some automakers manufactured vehicles that run on alcohol fuel. The Ford Model T, for instance, could run on alcohol, gas, or both but this was not the case after top oil companies influenced manufacturers into using gasoline.

Below are the two types of fuel alcohol:

  • Ethanol
  • Methanol

To build your vehicle engine to run on alcohol fuel, ethanol alcohol is the best option. Ethanol is made by fermenting sugars from organic sugar materials, including rice, corn, wheat, and sugarcane.

Methanol, on the other hand, can be distilled from wood and is commonly used in Indy-type race vehicles. It can also be sourced from petroleum but is toxic and can result in ingestion. Although methanol can power your car engine, it produces less energy than ethanol.

Can You Distil Alcohol Fuel at Home?

Yes, you can distill alcohol fuel from home, and is perfectly legal. You can distill alcohol as low as 40¢ per gallon according to your still size, grain cost, and fuel you use for powering it. So, how do you make distilled alcohol? You may check Instructables’ guide for creating distilled oil.

Alternatively, you can buy alcohol from most wholesale chemical supply companies. Alcohol you buy from a supplier is denatured, and this means that the manufacturer meets the government-approved standard make the alcohol unfit for consumption. Denatured alcohol should be treated like gasoline because it is poisonous and not fit for human consumption as food.

You would have to refer to the supplier to know the price but you can budget $1,000 (this price is stipulated and subject to change) for a 55-gallon drum of 200-proof ethanol. It is economical to purchase in bulk and save money. Most suppliers sell differently, so you want to compare the prices from various companies to save more money.

How to Modify Your Car to Run on Alcohol Fuel

For a start, you want to try this out on a vintage car. It also works on boats, lawnmowers, farm implements, emergency generators, and motorcycles. You can also buy a cheap car from Craigslist to test the project before extending it to your primary vehicle.

  1. Prepare your vehicle and conversion materials

Decide what car to use for this conversion. Of course, it must be a car that runs on gasoline. It should be your rickety but functional car.

If you have none, you can invest a few hundred dollars to get it online. You need an old car that barely runs or that you rarely use. Make sure not to use a vehicle you would need for transportation because the adverse effect of alcohol on the vehicle can stop it from running. Besides, you are not using gasohol here but alcohol which is far different from the gasoline your car is designed for.

The tools you basically need include the following:

  • Carburetor
  • Overhaul kit for carburetor
  • T valve
  • Manual choke kit
  • Fuel hose
  • Barb fittings (about 3) for fuel hose
  • Teflon tape
  • Sizeable gallon tank
  • Spark plugs
  1. Modify the fuel line

We assume that you have decided whether to make this fuel to alcohol conversion permanent or be able to use gasoline when it is readily available.

If you are converting your car to run on alcohol permanently, you have to modify the gas tank to alcohol. In this case, you will dry out and replace the gasoline with alcohol. You do not need a mixture of gas and alcohol. The reason is that both materials will not mix unless you completely get rid of water in the alcohol.

If you want the car to run on gasoline, then you want to install a dual-fuel system.

In this tutorial, we make the alcohol tank from a 5-gallon heavy-walled Nalgene plastic container. You can also use a metal container if you have any around. The size of the container depends on your car and what you want and you can mount it on the vehicle roof or trunk. Regardless of what you use for your alcohol tank, you need something sturdy, clean, and leakproof.

  1. Install a pickup tube for the fuel tank

You need to mount a pickup tube with a similar outside diameter as the existing fuel lines. You can measure the tube at about 1/16” from the bottom of your tank make it protrude at about 1” from the top. You will also need a vent tube for air to replace the liquid whenever it is consumed so that the tank does not collapse. Create a hole on the tank sizeable for the vent and fuel lines epoxy. You can also braze your pickup tube in place to the pipe plug depending on what material you use.

Install the tank. Place the tank where you want it in the car. Ensure to strap or fasten it securely to prevent the tank from overturning. You can weigh it in-between your back seats or anything to stop it from shaking. After mounting the tank, you want to make sure you can connect it to the existing fuel line. You can use a T-shaped valve, either the manual or electric valve with 2-3 inlets, depending on what you want.

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Mount the valve. You need to mount the valve somewhere practical. It can be on the inner fender or floorboard to keep the handle operational inside the car. In this case, you do not have to raise the hood whenever you have to switch from one fuel to another.

To reroute your fuel lines, you can use a fuel hose. Ensure to connect the hose to the T-shaped valve. You can use standard barb fittings and then apply Teflon tape on the threaded connections to prevent leaks. To install the T valve and change the fuel lines, mount the T valve wherever you prefer. You may have to install the barb fittings. Now, do the following:

  • Use the fuel hose to connect the alcohol to one of the T valve inlets.
  • On the inlet side of the fuel pump, remove the hose between the pump and the metal fuel line from the gas tank.
  • Using the fuel hose, connect the metal fuel line to the remaining T valve inlet.
  • Using a third length of fuel hose, connect the “T” valve outlet to the inlet side of the fuel pump.

You want to be sure that the lines are leakproof and secured without any moving component obstructing them. You can now switch between your fuel (gasoline and alcohol) system by flicking your valve.

  1. Disassemble your carburetor

The carburetor is the heart of your engine that feeds the appropriate air and fuel to the cylinders. We have the one-, two- and four-barrel carburetors. Note that every carburetor operates in the same way. Alcohol will burn efficiently with about a 9/1 ratio. What you want to do now after placing the tank is to remove, modify and replace the carburetor in this ratio.

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  • Decide what Carburetor to use. You can use your current carburetor from the gasoline or get a new one. Since you are experimenting, you can get a used carburetor. You also want to be sure that the carburetor you collect is compatible with your vehicle engine. You will need a carburetor overhaul kit compatible with your carburetor (check the carburetor body to confirm the compatibility). Usually, a carburetor overhaul kit contains check valves, accelerator pump plunger, new gaskets, etc., to make your carburetor perform excellently. You also get detailed instructions and every part uses a name and number for reference to make assembly easier.
  • Remove the carburetor. You should assess the engine before taking out the carburetor. Take note of the hoses and every connection so that you do not have difficulties reassembling them. Lose the carburetor bolts and store the fasteners safely.
  1. Enlarge your Carburetor metering jet

  • Determine the hole size of the metering jet. A metering jet controls the amount of fluid flow for a given pressure drop in a jet. Prepare an uncluttered surface to work on. Next, disassemble the carburetor enough to take out the main metering jets. Depending on your model, it could be challenging to reach the jets. Now, ascertain the hole size of the metering jets by checking the shop manual or measuring it. Alternatively, you can have an auto mechanic shop measure and enlarge the jets for you. Increase the jet diameter by 40% for alcohol (to keep the valve from burning because of an over-lean mixture). Now, test your car. If the mixture is rich and the jets are too large, install new jets enlarged at 35% or smaller (depends on your vehicle). Keep reducing the size by 5% until you obtain the required size.
  • Enlarge the metering jet. You might need a drill size chart available in most auto repair manuals to know the drill size to use. Using the drill, enlarge each jet using a drill press or a hand drill. Ensure to remove the jets from the carburetor before drilling them.

Instead of drilling your Carburetor, which can create problems when the tiny shaving falls inside the passages, you can buy stock jets suitable for your carburetor from an auto part dealer.

  1. Modify the float and reassemble the carburetor

Unlike gasoline, alcohol has more density and is heavier, which means that the float in an alcohol fuel will be higher in alcohol than in the same amount in gasoline. In this case, you have to add more weight or bend the float linkage to prevent your car engine from cutting out during turns for insufficient fuel.

Below are the ways you can modify your float for alcohol fuel:

  • Add weight to the float. To add weight to the float, weigh the entire float assembly using a balance. Secondly, weigh an epoxy glue or solder that is equivalent to 10% of the float assembly weight and attach it to the float top to distribute even weight.
  • Bend the float and inlet valve. You might have to bend the float severally to discover the correct float height. This method is quite tedious and you must disassemble the carburetor severally to get the correct float height.
  • Reassemble the carburetor. Finally, follow the kit instructions to adjust and reassemble the carburetor.

Modifying Your Car Ignition System for Alcohol Fuel

The ignition system controls firing and power production. It ignites the mixture of fuel and air precisely according to the piston movement. Pre-ignition pinging will take place if fuel and air mixture fires too early, which can damage the car engine. If the fuel/air mixture ignites late, the car loses power, and fuel is wasted.

Usually, a gas engine fires as soon as or an instance before the piston reaches the top of the stroke and gas then burns faster like an explosion. Alcohol fuel on the other hand burns more evenly than gasoline. Therefore, ignition becomes harder and takes longer to entirely vaporize and burn. In this regard, you have to cause the engine timing to fire earlier (advance) by loosening and turning the distributor in the opposite direction from the direction of the turning rotor.

What if you are unsure about where the engine rotor turns? Remove the distributor cap and have someone crank the engine. Take note of where the rotor turns and turn the distributor body to the opposite direction to advance the timing (cause to fire earlier).

Steps to Modify the Ignition System

  • First, loosen the distributor bolt until the whole unit can turn.
  • Turn the distributor about 1/16 to advance (cause to fire earlier).
  • Ensure that the distributor does not turn by snugging the bolt holding it down. Let it be such that you can still move the distributor with small effort.
  • Power the engine and get rid of leftover gas from the fuel line and advance the distributor further until the idle is faster and smoother.

You can check if the timing is okay by driving the car and listen to the engine pinging while accelerating. If you set it correctly, it should be just below the point the pinging disappears. Note that the level of advancement depends on your engine.

The Right Spark Plug to Use

You want to use spark plugs that are one or two ranges hotter than your engine. As mentioned earlier, an alcohol fuel does not ignite or burn as fast as gas. This means that you must increase the firing chamber temperature to improve how the engine ignites and burns alcohol fuel. Fortunately, you may be able to achieve this effect by using a spark plug that is one or two ranges hotter than what your engine used earlier. The term ‘hotter plug’ is used to refer to a spark plug that holds heat longer.

  • Iridium Spark Plugs
  • Designed to operate over a much wider heat range than ordinary plugs
  • Resists carbon buildup and pre-ignition
  • Patented triple gasket sealing process eliminates the possibility of combustion gas leakage

Spark plugs are made in three or four heat ranges. Two spark plugs can be the same type but use different heat ranges. The spark plug with a higher heat range has more heat dissipation rate and holds heat longer.

In essence, if you use a spark plug with a higher heat range, your car can receive more alcohol fuel to completely vaporize and improve the time it takes to warm the engine. This does not mean you should use a plug that is too hot. Also, ensure to inspect the plugs after a few miles to be sure they are okay for the car.

Resolving Cold Weather Starting Problems

Under cold weather conditions, alcohol fuel may not readily vaporize below about 70º F. If you do not live in a tropical climate, you want to get things right to start the engine in cold weather:

  1. Preheat the alcohol fuel. You can preheat the alcohol fuel by applying an external heat source to the fuel line or carburetor. Do not be afraid to try out any method that can heat the alcohol fuel temperature above 70º F.
  2. Prime with gasoline. You can use gasoline to heat the engine. First, install an extra windshield washer pump and reservoir. The washer pump uses a hose that connects to a spray nozzle or tube in the air cleaner lid. This fills the reservoir with gasoline and a drop of gas will fire the cold engine which will also run on alcohol.
  3. Manual choke. Hand choke can help the cold engine start-up. You can replace the automatic choke since the manual choke can pamper a cold engine. It also works to widen the choke so that you can leverage the window-washer priming method.
  4. Use gasoline to start the engine. If you modified your car with the T valve fuel system type, you can be able to start the car with gasoline. This method will use gasoline which can last for about a week. A smaller tank might use less than a gallon, and the alcohol fuel goes into the tank.

Common Symptoms, Causes, and Solutions

You might face common problems but each has a solution. The first thing you want to do is to fire up the engine for a test. At this point, you would have:

  • Fully modified and put the carburetor back in place.
  • Advanced the timing (you can always advance again if it is not OK).
  • Completed the fuel line changes.

Next, prime the carburetor with gasoline, fill the tank with alcohol fuel, and crank the car engine. When the alcohol fuel reaches the engine (now modified from gasoline to alcohol), feather the gas pedal to keep the car running. Do not set the idle until the engine warms up, then carefully back out the idle adjusting screws 1/4th turn at a time till you have a smooth idle. If your car uses double idle screws, turn both at the same level until the idle is smooth. Finally, test drive your car modified to run on alcohol fuel.

Now, you might notice some unusual symptoms. Below are symptoms to look for, causes, and what you can do to resolve:

  1. The engine does not start when cold

Possible cause:

  • The fuel vaporization quality is poor.

Possible solution:

  • Use a better alcohol proof (160 or more) if you do not already.
  • (Refer to the section on “Resolving Cold Weather Starting Problems” above for possible solutions).
  1. Dead engine when idle

Possible causes:

  • You did not adjust the Carburetor correctly.
  • Your spark plug heat range is not correct. If the spark plug is white, it is too hot for the car and if wet, it is too cold.

Possible solutions:

  • Follow the alcohol kit instructions to adjust the Carburetor.
  • Use the correct spark plug range.
  1. The engine pings under hard acceleration

Possible cause:

  • The timing may be too advanced.

Possible solutions:

  • Play around until you obtain the correct timing.
  1. The engine cuts out when you accelerate

Possible cause:

  • The accelerator is not at full pump.
  • The float level is low.

Possible solutions:

  • Adjust your accelerator pump to a longer stroke.
  • Add more weight or raise the float.
  1. Dead engine when you make a corner turn

Possible cause:

  • The float level is low.

Possible solution:

  • Add more weight to the float.

Final Thoughts

With all these in place, you can start your car now running on alcohol fuel. Note that you can make modifications, or apply more improved changes contrary to this guide for modifying your car to run on alcohol fuel. You might also need an assistant to simplify the task and reduce the project time.

Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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