Mother's Alcohol Fuel Preheater

Adding a fuel preheater to your alcohol-powered vehicle improves combustion and can improve fuel economy. It should take about an hour to assemble and install the unit described here.

| January/February 1980

  • 061 mother's alcohol fuel preheater
    TOP LEFT: Wrap the soft copper line tightly around the pipe and solder a continuous bead at the ends. TOP RIGHT: The components you will need for the fuel preheater. BOTTOM LEFT: The preheater spliced into the radiator hose, with fuel lines joined to the copper preheater coil. BOTTOM RIGHT: The flow meter installed in MOTHER EARTH NEWS' alcohol-powered truck indicates that fuel consumption is about 4.8 gallons per hour—or 11.4 miles per gallon—at 55 MPH.

  • 061 mother's alcohol fuel preheater

In a previous issue of this publication, we explained how to make a cold weather starting system for an alcohol-powered vehicle. 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 EARTH NEWS' 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 alcohol fuel 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.

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