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Construction ideas for this concept? Answered

Recently, I have been working on a gas 'vaporizer' that evaporates gas before being fed into an engine. During my short-term experiment, I found that this saves ~70% (+-20% for crudity of measurement.) This works because the vapors will burn more thoroughly and cleanly, leading to higher apparent efficiency.

Below is a basic diagram of how the system works. You can see there is a container that is half-full with gas, and a hose goes down with many small holes. As the engine's compression draws a vacuum on the container, air will come up through the holes. As it rises, the gas-air surface area rises dramatically, leading to the vaporization of gas. To further increase the surface area, I also added a felt liner on the inside to allow the gas liquid to rise and evaporate.

The final mixture ends up very rich, so to compensate, a 'T' fitting has been added to allow air to mix in with the vapors/fumes. Some valves have also been added to control the air inlet (similar to a 'choke') and the amount fed to the engine (similar to a throttle. In fact, it is possible to use the original throttle or choke as a throttle on the carburetor on my tractor!)

The problem is: My original design utilized a plastic folgers coffee can, and the flimsy plastic top was hot glued to a thicker plastic cutout for strength and support. Since most glues will dissolve in gasoline, including hot glue, it could not be used. most did not hold anyway. I also tried JP weld plastic cement and it did not hold at all. I had to trash this build. I did, however, get enough use to run the tractor for several minutes while testing gas use. I found that the tractor used nearly twice as much simply running on gas than the fumes. I did not have the float valve and electric pump hooked up with the prototype. Also the 3/4in housing I used may be a bit constrictive and also seems to get slightly damaged by the gas. It will not be a long-term solution. 

So I need to redesign the project, and I am thinking of using a 1-3 gallon bucket that is sealed or a gas tank. I need good almost air-tight seals on everything. I am asking for any ideas related to the construction of this device and any tips you may have.


I remember in mechanics class a guy trying the same as you brought in this old cordoba. He just added basically a spacer between the carb and the engine that was heated with an extra coolant hose. Then he placed a metal screen in the middle and the IDEA was (not sure it worked considering he donated it to a mechanics class) the second that the gas hit the screen it would then vaporize and be sucked through the screen. It's very simple and then there is no worry of it being vaporized before it is used. I'm curious to see how this works!

I believe that your best option would be to use a vaporizer, the part that replaces the carburateor in lpg conversion kits. That way you would have all the engineering pretty much done, with the speed regulation, the butterfly valves, etc.


4 years ago

OK, I have bought a $4 empty paint can at lowes, as Burf suggested. I never would have guessed that these are sold empty like that!

Now, I need to figure out how to either make butterfly valves, or some other solution to let me let a large quantity of gas at low pressure differentials flow very easily. I think the simplest method is to use a short piece of thin-walled hose, and have a large crimping handle to pinch the hose shut. Although I question the reliability of this method.

Also, under what conditions (with respect to how loaded down the engine is) is the engine putting out the most HP for the gas used, AKA, when efficiency is the highest? I think it is when the engine is under a very heavy load where the torque output is high and RPM is somewhat low. I would think that maximizes the use of the internal combustion.


4 years ago

I think I have decided to use a metal paint can for the container. Also, I am having trouble with what materials I should use for the piping. What is the type of hose called that is used in vacuum cleaners, that type of hose looks very suitable if I can insulate it from the heat of an engine. But it being sold as vacuum hose, it is expensive. For a lawn mower, I think I need 1 inch piping for the fumes.

Also, I cant find simple butterfly valves like the ones in carburetors that can be controlled using servo motors. What could I use instead? Solenoid valves seem to be for higher pressures and too small. I thought about making butterfly valves, but I do not have materials or the tools. I might end up creating them anyway. they will not be as air-tight as I hope, but will probably do if I can cut the aluminum sheet metal I have precisely.


4 years ago

There are epoxy glues that work in gasoline. They are often used in gas tank repair kits. These glues will harden while submersed in gas and remain impervious to it.

That being said I am not sure about the practicality of your idea. Modern fuel injection systems are designed to turn the fuel into a mist that vaporizes in the cylinder. This is especially true of diesel engines. Some of the new piston designs I have seen use a cone shape on the piston head to cause the gas/fuel mix to swirl and mix together when the pistons compresses. They have gone to great lengths to develop methods that completely mix the fuel and air so as to maximize the efficiency. I don't see how you are going to improve on that work.

PS. Do be sure to attach a ground wire to whatever you are working with. Static charge can set off vaporized gasoline. When I worked with solvents we had to use a ground strap to connect 2 containers together when we poured solvent from one into the other. The act of pouring the solvent from one to the other generated enough static charge between the 2 containers that it could ignite the solvent. Its dangerous stuff.

Thank you for the tips. I will be sure to keep safety in mind, and look into the gas tank repair kits.

Like I said, I did in fact see a 70% savings on fuel useage by marking the container at different levels. While it is true that fuel injection does a decent job of creating a good mix, it is not perfect, and apparently one can achieve almost 200 miles per gallon with a larger version of this system, or so the rumor has it. I found this hard to believe, but after short tests on my mower I think I can expect ~ 40 MPG from a 15 MPG truck. There is a lot of info on the internet about this device, too.

Wait until you see what power is being delivered. If you really think that this hasn't been done and long discarded, i know a great bridge I can sell you for only 10,000 bucks.


And the explosive potential of vaporized gasoline in a flimsy, flammable plastic container makes me shudder.

No kidding! But gas tanks are also made of plastic. I don't see how the mixture could ignite unless the float switch is not gas-proof and the contacts inside spark due to inductive kickback from the pump. This can be stopped by adding a snubber circuit (reverse biased diode?) And of course having all electronics outside of the vaporizer.

Real plastic gas tanks are made of PEX (cross linked PE;) thicker by an order of 8 to 10, flame, fuel (and additives,) pressure resistant and have unitized, molded connector fittings.

I'm guessing plastic coffee containers are made of HDPE. How well it will stand up to chemical and heat deterioration, internal pressure fluctuation caused flex (fuel volume, air and hydrocarbon expansion and contraction) and integrity failure due to vibration is anyone's guess.

Personally, I just don't see a plastic coffee container as a viable tank for vaporizing gasoline.

Also, HDPE and PEX, at least what I found on wikipedia, are both under the family of polyethylene. The only difference I found is that the cross-linked bonds between the chains of molecules create stronger bonds that make it more temperature-resistant.

Which is precisely why I am asking this question to find a better solution. It seems to withstand pressure differential well enough, and I think the plastic is resistant to gas enough to handle it. However no glue I have tries has worked. I will either need to find a suitable metal container, or figure out some other solution. I am confident a small bucket with a sealed lid would work nicely, but any ideas are welcome!

It is funny you mention flex, since the coffee can warps and deforms when initially starting the engine. With each cycle, it gets compressed as the pressure inside changes rapidly.

I suppose a 1 gallon steel paint can would work. You can solder the lid and any fittings in place. That's certainly better than most commercially available adhesives.

You can buy clean/new empty paint cans at Lowe's, Home Depot and probably online.

it isn't possible to get an explosion in the gas tank because the vapor is saturated, and the air displaced.

I agree. Although gas vapors inside may still be flammable enough to cause problems since air is allowed to enter though the bubbler. It is still way too rich a mixture, and worst case scenario just burst into flames popping the lid off.

During my short term tests I found that fumes deliver very similar performance to gas. I was able to drive and accelerate up a hill at the same speed as running off fumes. the mower deck also sounds the same. I need to get more specialized equipment for determining the HP Under different Loads.

I know it has likely been done before, and looking at the design of the carburetor, it appears to do just that.

Maybe a pressure cooker would work for your container.