Question:How come there's so much "pollution junk"
on my engine?
Answer:Because the internal combustion engine is an inherently
dirty design. But with the right controls and add-on devices,
it can run exceptionally clean -- not as clean as a zero emissions
vehicle like an electric car, but clean enough so as not to pose
a serious threat to the environment.
WHY THINGS ARE THE WAY THEY ARE TODAY
The automobile that created our mobile society and gave us
the freedom to travel where we want, when we want and with passengers
of our choice, has now become the object of environmental scorn.
The internal combustion gas and diesel engines that power almost
all vehicles today are often blamed for everything from air pollution
to global warming. Consequently, the internal combustion engine
has become a prime target for regulatory crucifixion.
We hear a lot of so-called "facts" about the automobile's
role in pollution. We hear statements like "nearly two-thirds
of the total carbon monoxide and half the hydrocarbon and nitrogen
oxides polluting our atmosphere comes from motor vehicles."
We also hear alarmist statements like, "three out of five
Americans face lung damage from ozone-polluted air."
We can't argue with the evidence that says automotive emissions
are a major contributor to urban air pollution. You don't need
a Ph.D. in chemistry to experience firsthand the nasty effects
of exhaust pollution in a traffic jam. But there aren't many Americans
dropping dead in their tracks from breathing polluted air. It
may be a contributing factor to lung disease and respiratory ailments
in some people. But deadly? Not unless you're running an engine
in a closed garage.
It's simply not true that all motor vehicles are polluters.
The fact is that thanks to all that "pollution junk"
on your engine today's cars produce far less pollution than ever
before.
Pre-1963 vehicles were the worst because they lacked any emission
controls whatsoever. In 1963, positive crankcase ventilation
(PCV) was added to recycle the blowby vapors in the crankcase
back into the intake manifold so they could be reburned. This
virtually eliminated crankcase emissions as a source of air pollution.
Sealed fuel systems and charcoal canisters showed up in 1971,
which reduced evaporative emissions to zero. In 1973, exhaust
gas recirculation (EGR) was added to reduce oxides of nitrogen
(NOX) in the exhaust.
An even greater change appeared in 1975 when the catalytic
converter (which requires unleaded gasoline) was introduced. The
converter greatly reduced unburned hydrocarbons (HC) and carbon
monoxide (CO) levels in the exhaust by "reburning" the
pollutants. Switching to unleaded gas was necessary because lead
poisoned the catalytic agents, which also eliminated lead as a
significant exhaust pollutant.
In 1981, onboard computers for closed-loop running and three-way
oxidation/reduction converters were added to most cars, which
cut CO and NOX emissions by another 50%. By the mid 1980s, fuel
injection arrived. And today we have engines that can meet even
the toughest low emission standard yet conceived -- except for
zero emissions which the internal combustion engine cannot meet.
The tailpipe emissions from late model cars (1981 and later)
with computerized engine controls and three-way catalytic converters
are only a fraction of the older pre-emissions controlled cars.
Today's cars produce 96% less HC and CO, and 76% less NOX than
their pre-emission counterparts.
Additional reductions being phased from 1994 through 1998
model year cars and light trucks are further reducing emissions.
The federal standards up through 1993 allowed no more than 0.41
grams per mile (gpm) of HC, 3.4 gpm of CO and 1.0 gpm of NOX for
the first 50,000 miles. The new standards slash these limits
by almost half again: CO is cut to 0.25 gpm, while HC and NOX
drop to 0.4 g/m.
So what do all these numbers really mean? It means a 1975
to 1979 model car puts out roughly as much HC and CO pollution
as four new cars; a 1972 to 1975 model year car produces as much
of these pollutants as seven new cars; a 1968 to 1971 model year
car produces pollution equivalent to 10 new cars; and a '63 or
earlier pre-emissions controlled car pumps as much crud into the
atmosphere as 25 or more new cars! These comparisons assume that
a vehicle produces no more pollution that it did when new -- which
is usually NOT the case once an engine accumulates a lot of miles.
Emissions go up with age. It's not unusual to find high mileage
engines in older vehicles (1981 and earlier) that are belching
out the pollution equivalent of 100 new cars!
So be glad your engine has all that pollution junk on it.
We can all breathe easier as a result of it.
