Mother's Alcohol Preheater

By the Mother Earth News editors

In the last issue of this publication, we explained how to make a cold weather starting system for an alcohol-powered vehicle (see MOTHER NO. 60, page 86). Now, we'll go on to detail an uncomplicated device that will not only warm the liquid alcohol to provide smooth operation in frigid weather, but will save you precious fuel in the bargain!

The gadget is merely a preheater that uses the engine's cooling system to warm the fuel just before it flows Into your vehicle's carburetor. Although such a warmup isn't really necessary in MOTHER's relatively temperate climate, there are folks in other parts of the United State—sand especially Canada—who will appreciate the benefits that our easy-to-make preheater can provide.

HOW IT WORKS

Cold alcohol from the fuel pump is —rather than being routed directly to the carburetor—"detoured" through a length of copper tubing that's coiled around a short section of copper pipe. This piece of conduit, in turn, is spliced into the upper radiator hose of your automobile.

Naturally, as the fluid within the engine's cooling system reaches normal temperature (which may be—depending on your vehicle— anywhere from 160° to 195°F), the warm liquid transfers a good deal of its heat to the copper-pipe—and—tubing assembly ... where, of course, the alcohol fuel can pick up the warmth while on its way to the carburetor.

Because ethanol doesn't vaporize as well as does gasoline (and such poor vaporization is, of course, aggravated by low temperatures), the preheating device actually serves two purposes: [1] It allows warm fuel to enter the carburetor, which makes that "atomizer's" task easier and prevents cold weather carb problems ... and [2] the more efficient "mixer", in turn, provides increased fuel vaporization within the intake manifold, which improves engine economy. (The powerplant's inlet piping will, of course, become warm itself soon after the vehicle starts running, but the fuel preheating process does provide another helpful "boost".)

BUILD IT YOURSELF

The copper ethanol—warmer takes less than an hour to make and install. Start by cutting a piece of 1-3/4" O.D. (outside diameter) copper pipe to about 5" in length. (The external diameter of this conduit section will, of course, be dependent on the inside diameter of your upper radiator hose, since the hose must fit snugly around the ends of the pipe.) Try to use conduit with an approximately 1/8"-thick wall ... to prevent the pipe from collapsing when you begin to force the softer tubing around it.

Next check the diameter of the fuel line, and cut yourself a 42" length of copper tubing with the same diameter (most automobiles use 5/16" or 3/8" line). Clean the metal tube off with steel wool, then wrap it tightly around the 5" length of conduit that you cut previously. (Be sure this pipe's surface is also thoroughly cleaned.) Six full coils should be sufficient, but remember to leave a 1-1/2" "tail" at each end of the copper "spring" to affix a fuel line inlet and outlet. (By the same token, allow some room at both ends of the large pipe ... to use when you splice your preheater into your cooling line.)

Once that's done, heat the 5" pipe with a torch, brush some paste flux onto both copper surfaces, and sweat the coils to the pipe with 50/50 general purpose plumbing solder. Of course, every loop doesn't have to be completely fastened to the conduit, but it would be a good idea to attach at least the extreme end coils with a continuous bead. (The solder not only holds the copper coils fast, but also assists the heat transfer between the tubing and the pipe.)

From that point it's just a matter of installing the unit in your vehicle. Locate a 3-1/2" length of rubber radiator hose that fits snugly around the large pipe, then clamp the conduit to this flexible coupling, remove your existing upper radiator hose at the engine, and fasten the new assembly to the thermostat housing. Complete the junction by reclamping the radiator hose to the preheater's free end.

Your fuel line can be hooked into the system in the same manner. It your auto already has a flexible neoprene hose, simply cut it and fasten the ends to the coil's inlet and outlet fittings. However, if your car's fuel lines are steel, you'll have to remove a small section of the metal "hose" and use two short lengths of neoprene tubing—and four small clamps—to attach the existing line to the warming loops.

TRY IT OUT

As the ethanol fuel passes through the coils, it will naturally gain heat ... but—even if the coolant within the engine approaches the boiling point—the warmth will never completely transfer into the moving fluid. Ideally, the alcohol's temperature should not be allowed to rise over the boiling point of that liquid—which is about 173°F—since this would cause a vapor lock condition within the fuel lines and carburetor ... but warming the ethanol to well above the ambient temperature is fine. (Actually, with six coils incorporated into the preheater, the temperature of the fuel will rise only to about half the temperature of the engine coolant.)

As MOTHER's truck is equipped now, the preheating device improves fuel economy by up to 11% ... raising the average alcohol miles-per-gallon from 10.1 to as high as 11.4 at 55 miles per hour. Now, a total of 11.4 MPG might not sound like big news, but for a truck—and especially one that gets an absolute maximum of 13 MPG (unloaded) using gasoline—this figure is somewhat impressive.

There's a chance that your vehicle's alcohol mileage might be increased further by adding to the number of coils in the preheater ... but—after a certain point—such additions become ineffective and could result in engine hesitation and power loss when the accelerator is depressed. And, of course, you may have to experiment to get the best balance of engine economy and performance. However, we're sure you'll find that—even if you're not looking for high mileage exclusively—MOTHER's preheating device will help your alcohol-powered vehicle operate better during the winter season.

WARNING: BE ADVISED THAT MOTHER'S FUEL PREHEATER IS FOR USE IN LCOHOLPOWERED VEHICLES ONLY. IF YOU TRY TO USE THE HEATER WITH GASOLINEPOWERED VEHICLES, YOU UN THE RISK OF A DANGEROUS FIRE, SINCE GASOLINE IS A GREAT DEAL MORE VOLATILE THAN ETHANOL.

Produce eight gallons of alcohol fuel per hour at a minimal cost.

MOTHER'S SIX-INCH-COLUMN STILL!

Bigger may not always be better, but in the case of alcohol fuel stills for the small farm or homestead, it does pay to take advantage of the production benefits that size can offer. That's why—after designing this publication's first practical alcohol distillery (see "MOTHER's Wood-Burning Still", issue 58, page 76) —researcher Clarence Goosen immediately began working on a new, bigger apparatus . . . which, as it turns out, not only utilizes all the best features of the original three-inch-column still and improves upon them, but Is capable of producing between eight and ten times more fuel than could the initial model!

Now you might think that—because the new still has a capacity that's 1,000% greater than that of the old one— it would cost that much more than its predecessor, too. However, because of the fact that the larger version was purposely designed to use less copper and—for the most part—common (or scrap) metal stock in its construction, you can probably build the entire unit for about $500 if you're a capable scrounger! (And this figure Is, of course, barely twice the cost of assembling our smaller still.)

MOTHER's latest alcohol-maker is wood-fired, and has a mash capacity of 275 gallons (the storage vessel is no more than a salvaged fuel oil tank). Like its smaller relative, the new model has a stripper and a reflux column ... however, in the most recent design, both are made from inexpensive 6" thin wall tubing rather than costly copper.

Also, the still's efficiency has been Increased by replacing the marble packing—used in the three-inch column model—with commercially available 5/8" "Pall rings" (they're about 25% more effective than marbles), which provide 131 square feet of surface area per cubic foot and allow for 90% free gas space. (In effect, this means that the rings give us a near-perfect balance of two desirable features ... since we need plenty of surface area to "strip" as much water from the alcohol vapors as possible, yet we must also provide a fairly large volume within the column to achieve a high capacity flow rate.)

Another reason MOTHER's six-inch-column still works so well Is that it was designed to maintain temperature equilibrium. In other words, even though the distillery's volume-per-hour output is increased—since more alcohol vapor is forced into the column than it can handle on its own without overheating the correct temperature balance is accomplished (from the variable boiling point of the mash at the bottom of the column to 175°F at the top) because the column contains two heat exchangers which remove much of the warmth but leave the alcohol distillate within the column.

Furthermore, the still is not only extremely efficient as is, but also flexible enough to incorporate many different modifications. For example, although we used a plate steel firebox (to facilitate transportation of the still), you can cut expenses by constructing your oven of stone and/or brick. Also, the size of the mash tank Isn't critical ... a larger container could be used if the builder desired the extra capacity.

By the same token, you can up the output of the still by increasing its column size to an eight- or ten-inch diameter. You see, the working principle will remain unchanged ... as long as you maintain a height-to-diameter ratio of about 24 to 1 (thus an eight-inch column must be 16 feet in height, and a ten-inch conduit would have to be 20 feet tall).

But the best news is yet to come: This low-cost still, even though it can deliver up to eight gallons per hour of distillate (and more if you choose to upscale it), is also capable of producing a 175- to 190-proof Product ... which is ideal for homemade fuel alcohol use!

EDITOR'S NOTE: If you feet that you need a large capacity still for home or farm alcohol production, you'll be pleased to know that MOTHER will have a complete set of detailed, step-by-step plans available for the construction of the distilling apparatus shown here by February 1, 1980. just send your request for MOTHER's six inch-column still—along with $15—to Mother's Plans, P.O. Box A, East Flat Rock, North Carolina 28726.

And-should you choose to get involved in alcohol fuel production-be sure to comply with the new, and much less restrictive, regulations pertaining to fuel manufacture that are enforced by the Treasury Department's Bureau of Alcohol, Tobacco, and Firearms. Information—on applying for the necessary permit, etc.—is provided with every set of MOTHER's still plans.