ROBERT G. HOWARD wrote:
> The air pump simply dilutes the exhaust.
No, not true at all. Common misconception.
The air pump is there because some hydrocarbons leave
your combustion chamber unburned. Essentially, raw gas
leaving the exhaust that is otherwise being released
into the air.
This fuel didn't burn because it didn't come
accross oxygen in the combustion chamber. Burning
is when fuel combines with oxygen.
The air pump is there to provide oxygen into the hot
exhaust manifold (and catalytic converter if so equipped).
While the raw hydrocarbons in the exhaust are still
hot, the will chemically "burn" if oxygen is introduced.
The catalytic really helps here. The catalyst allows
the raw fuel to combine with air-pumped oxygen even
at low temperatures. (low being relative, the cat
is still damn hot but it's no combustion chamber)
In summary, the air pump provides oxygen to the
exhaust that allows more complete chemical burning
than if the air is just blasted out the exhaust into
the cool atmosphere.
Incidently, if you still beleive in dilution,
check the output of the air pump on a car that
has a working one. The actual amount of air that
comes out of one of these things while running
is not a hell of a lot.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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