Brazil's Alcohol-Powered Cars

In the early 1980s, Brazilian automakers were working intensively on the development of alcohol-powered cars.
By the MOTHER EARTH NEWS editors
November/December 1980
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Alcohol powered cars like this Chevrolet from General Motors drive no differently than gasoline-powered cars.
PHOTO: MOTHER EARTH NEWS STAFF
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Earlier this year, the Brazilian auto industry began marketing alcohol-powered cars. But, surprisingly enough, fuel from farms isn't new to that nation's motoring scene. In fact, a minimum of 5% alcohol has been blended with the country's pump gasoline — though somewhat erratically, because of variations in the sugar cane harvest — since 1931! And, as a result of the nation's adoption of a "pro-alcohol" program in 1975, as much as 20% of each gallon of auto fuel now sold in Brazil is pure ethanol.

The gasoline blends never affected the motor industry directly, because a standard car needs no engine modification in order to burn such hybrid fuels. But in light of the government's ultimate goal of replacing petrol completely with 185-proof alcohol, Brazilian auto companies suddenly found themselves faced with a major decision: either develop alcohol-powered cars or lose much of their market.

The Solutions

MOTHER EARTH NEWS' editors visited with representatives of General Motors and Volkswagen of Brazil to determine precisely what the industry had done to produce reliable ethanol-burning cars and trucks. Naturally, each factory had its own way of satisfying the technical requirements set by its engineers, but — predictably — the mechanical alterations themselves were virtually identical for every motor manufacturer ... which serves to reaffirm the fact that alcohol fuel technology is now well beyond the "by guess and by gosh" stage.

The automakers directed their attention toward eight areas of modification:

[1] Increasing the compression ratio. Since the "octane" rating of ethanol is well over 100, engine compression can be raised to take advantage of the fuel's antiknock qualities. Although the alcohol/ water blend is capable of withstanding a 15-to-1 ratio, the factory-produced ethanol engines don't exceed 10.5 to 1; costly forged components would be required to do so, and fuel mileage figures don't increase appreciably when compression is raised to the upper end of the possible scale.

[2] Preheating the intake air. In order to help vaporize the alcohol, heated air (up to 210°F) is taken from a jacket surrounding the engine's exhaust manifold and directed into the air filter shroud. This flow is controlled by a vacuum-sensitive valve that provides cooler ambient air — at wide open throttle — to prevent ignition ping and deliver a denser fuel mixture charge under acceleration.

[3] Heating the intake manifold. Again, this change helps alcohol fuel to vaporize efficiently. In water-cooled engines, hot water is routed through chambers in the manifold walls. In air-cooled models, the intake "runners" are simply shortened to a minimum to reduce heat loss.

[4] Recalibrating the carburetor. Because the ideal air/fuel mixture for ethanol is 9 to 1 (as opposed to 14 to 1 for gasoline), the main jet, idle circuit, power valve, and — in some cases — the accelerator pump stroke have to be modified to supply more fuel to the engine. (Certain carburetors must also have their internal passageways bored.)

[5] Hardening the valve seats. Since alcohol doesn't contain the lubricating elements that gasoline does (although the presence of water in the fuel does help compensate for this lack), the engine's valve seats are induction-hardened or fitted with stainless steel inserts. [EDITOR'S NOTE: Cars built in the U.S. since the early 1970's are already so equipped, and older cars "weaned" on leaded gasoline have likely absorbed enough lubricant to provide a suitable cushion.]  

[6] Modifying the fuel system materials. Ethanol, especially in the presence of water, may cause eventual corrosion in various parts of a conventional fuel system. To forestall that problem, the fuel tank and pump and carburetor bodies are lined with a thin bronze coating in place of the lead/zinc veneer which is normally applied at the factories.

[7] Making ignition changes. Because of the antiknock qualities of hydrated alcohol, initial timing is advanced from 4 to 8° over normal settings. In addition, the distributor advance curve is recalibrated to take advantage of the fuel's high "octane" during times of heavy acceleration. A high-intensity ignition coil is also used — along with "hotter" spark plugs — to help overcome the ethanol vapors' resistance to ignition.

[8] Constructing cold-start systems. Since alcohol's reluctance to vaporize is accentuated in cool weather, the ethanol powered vehicles are fitted with starting aids for cold engines (which are used at temperatures below 55°F or so). Direct gasoline injection down the throat of the carburetor is common now, but alternative methods (based on increased fuel vaporization and auxiliary heating) are currently being researched so that only one form of liquid energy — alcohol — will be needed to operate the car.

Our test drive in an alcohol-powered Chevy sedan — despite our eager anticipation — proved rather unexciting ... not through any fault of the car, but because the excursion was virtually no different from a spin in any conventional automobile. And if it hadn't been for the slight, sweet odor noticeable at the rear bumper, we'd never have known we were operating a renewable-fuel-powered vehicle! The only drawback of such cars seems to be that they use about 15 to 20% more fuel than their gasoline-powered counterparts ... though this increased consumption is offset by the fact that Brazilian ethanol is about 30% less expensive than is the petroleum derivative. On the positive side as well, the fledgling autos boast standard warranties and maintenance schedules, and initial vehicle costs are in line with conventional cars.

And to the Future?

Naturally, the Brazilian government is doing all it can — by monitoring alcohol quality and offering reduced licensing taxes and easy credit terms — to promote the purchase and use of the new models. But responsibility still falls on the manufacturers to improve fuel economy and reduce exhaust emissions (which, though already far below the levels spewed out by gasoline engines in that country, still concern a growing number of ecology-conscious Brazilians).

In the meantime, don't be surprised if you start to hear a lot more in the coming months about what's being done in South America (and perhaps what should be done in North America!) to ease the energy crunch!


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