The Modern Quest for Fire
Story by David Zemla
Surging from zero to 40,000 volts in under 100 microseconds, electrons stack up on the center wire before arcing to ground and igniting a volatile mixture of air and fuel into an explosive release of energy. Sounds like some sort of science fiction weaponry, but if you ride a bike, this process occurs thousands of times per minute inches from your crotch. Yes, we speak of the venerable sparkplug and the perilous task it must complete in the name of internal combustion.
From the beginning, sparkplugs have been a bit of a puzzle. Their origin is even a little fuzzy, although most sources credit Robert Bosch and company with the first successful production over a century ago (Bosch owns the first sparkplug patent from 1902). During the preceding 100+ years, the basic concept has remained the same, while the technology surrounding it has become increasingly complex. The need for maximum efficiency and longevity has turned a simple electrical short into a modern quest for fire.
To better understand what a sparkplug does, one must first realize what it does not do. No matter the marketing hype, a plug cannot generate more voltage or a hotter spark. This is the function of the coil. Neither does a plug produce heat, when in fact it does just the opposite. These and other myths have caused more then their fair share of confusion. The very nomenclature used to classify sparkplugs (hot or cold) is in part to blame for some of the mystery. In reality, a plug must operate at a set temperature of approximately 900 ~ 1500 degrees Fahrenheit, weather it is in a stock bike, a race bike or your lawnmower. Hot or cold in this case is actually a reference to the plugs ability to transfer heat from its firing end into the cylinder head surrounding it and has absolutely nothing to do with the spark temperature. read more...
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