What's wrong with this
picture? I am walking through the staging lanes at high
noon on a sweltering summer day. All around me people
are wearing shorts and T-shirts, with wet shop rags
wrapped around their foreheads to keep the heat at bay.
Super Comp drivers sit in their dragsters with umbrellas
strategically placed to ward off the sun, while electric
fans circulate the heat inside a dozen Super Gassers
like convection ovens. As I head toward the starting
line, I hear engines running on all sides as racers warm
up their engines.
Wait a minute! It's hot enough to cook an omelet on the
starting line, so why are drivers warming up their
engines?
It's no wonder that some racers have problems keeping
their engines cool in the summer. If the temperature
gauge is already at 160 or 180 degrees when you pull out
of the staging lanes, chances are it will be pegged by
the time you get to the time slip booth.
Some racers believe that a warm engine makes more power
than a cold engine. Others think that a warm engine is
more consistent. In fact, heat is the enemy of
performance. A motor will make more power if you run it
cold - and it can still be consistent. |
My fellow back-page columnist
Warren Johnson has described the chemistry of internal
combustion in detail. An engine is really a vessel that
contains the energy released by chemical reactions.
Petroleum is the remains of prehistoric plants, plankton
and protozoa. Eons ago, these organisms banked the sun's
energy in their cells. We harvest this stored energy to
heat our homes, cook our dinners and propel our race
cars.
As W.J. noted, gasoline molecules release energy when
they break down into water and carbon dioxide - lots of
energy. Every gallon of gasoline contains roughly
114,000 British Thermal Units (BTU) of heating value,
enough energy to raise the temperature of 1,000 pounds
of water by 140 degrees.
Where does this energy go? Roughly 25 percent is
converted to useful work, five percent is used to
overcome the engine's internal friction and five percent
is radiated directly into the air. The largest portion,
about 35 percent, goes out the tailpipes as exhaust
heat. The remaining 30 percent is heat that must be
dissipated by the engine's cooling and lubrication
systems.
Most drag race cars have cooling systems that are
hard pressed to deal with such a
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