We may soon get an oil additive that actuallydoes what it's supposed to
do.

Additive gives improved mileage, less smog
Science News
Jessica Gorman
 
 
A chemical normally known for its role in the manufacture of synthetic
rubber may lead to cleaner-burning, more-fuel-efficient cars and trucks.
 
An experimental fuel additive reduces car emissions by 70 percent.
 
Automobiles using the polymer additive, called polyisobutylene, decrease
their emissions by 70 percent, says Paul F. Waters of American
University in Washington, D.C. What's more, mileage goes up 20 percent,
while horsepower increases 10 percent, he says.

Due to the emissions improvements and fuel savings, Waters says,
polyisobutylene "reduces the number of gases that potentially lead to
global warming."
 

Waters reported the results in late August, 2005 at the 220th national
meeting of the American Chemical Society in Washington, D.C.
 

Gasoline is a menagerie of hydrocarbon molecules that differ in size and
shape. Short molecules generally burn very quickly, causing temperature
and pressure inside an engine to rise in a dramatic spike. That creates
engine knock and emissions of nitrous oxide pollution. Meanwhile, longer
hydrocarbons burn more slowly and incompletely, which raises exhaust
temperature and leaves remnants of hydrocarbons that contribute to soot
and other forms of pollution.
 

Polyisobutylene appears to slightly delay the burning of short
hydrocarbon molecules, which then hasten the burning of the longer
hydrocarbons, Waters says. With the additive, therefore, the fuel burns
more completely and engine and exhaust temperatures drop significantly.
 

Waters suspects that polyisobutylene changes the surface tension of fuel
droplets, preventing short hydrocarbons from immediately vaporizing when
gasoline is sprayed into the engine. The delay apparently is "long
enough, so that. . .the two components evaporate more or less in the
same physical region in space and then they burn more or less together,"
says Waters.
 

"I think Paul has some intriguing results that could be very promising
for the automotive industry," comments Graham Swift, a polymer chemist
and independent consultant outside of Philadelphia. "It sounds
delightfully simple and promising to me. We tend not to look for simple
solutions."
 

"What I like about his approach was that he looked at combustion, and he
looked at what controls combustion, and then applied it to the internal
combustion engine," says Swift. With better control over the fuel
droplets, Swift says, "the better your combustion, the better your fuel
consumption, the better your automotive horsepower, the less incomplete
combustion you get, and that means you've got less noxious fumes coming
out."
 

So far, Waters and his colleagues have tested the additive on a dozen
automobiles in three states and several other countries. Waters points
out that 50 other cars also have shown improved performance with the
additive.
 

Waters says the mileage benefits could pay for the cost of the fuel
additive—perhaps 10 cents a gallon, he says. Polyisobutylene works
well in diesel engines, too, he adds.
 

"This is of course useful for global warming, but it's also useful for
the vehicle and the engine itself," says Waters. "When the engine
operates at a lower overall temperature, there's less wear and tear on
all the parts. The less temperature that you impose on any of these
devices, the longer they're going to last, and in principle, the less
your repair bill is going to be."
 

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"Sometimes, when you're up to your butt in alligators, it's hard to
remember that the intial objective was to drain the swamp."  
~ Unknown ~