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Old 10-07-2008, 12:56 PM   #33 (permalink)
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I fail to follow your thinking. Once the spark is initiated, the impedance drops, a circuit component switches in a capacitor that delivers current to prolong the spark. The capacitor initial charge of 300-400V and 1uF provides the energy. I do not have a trace however visualize the side profile of a Dodge Intrepid. The back of the car is the initial spark the front bumper is the end of event.

In the flyback case a circuit designed for 10-40KV at low current, at spark, sees a drop in impedance and a voltage less than 50V. Now what! There is a huge mismatch in the circuit impedance.

ConnClarke brings up a good point multiple sparks help. They do this because the flame starts in two places. Speeding flame burn enables improved timing and centering of the energy delivered by the power stroke. If the flame is too slow and timing retarded, some combustion happens in the exhaust wasting energy. It is difficult to find the room in head for two plugs in multi valve (4) engine. Instead combustion chamber design is used to speed flame travel.

A correctly designed combustion chamber with correct mixture, and modern (electronic direct fire or COP) ignition system works quite well. A long duration spark that erodes plugs is not necessary to keep the fire burning!
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