ngk dr8ea vs ngk d8ea
#11
02-14-2007, 09:15 PM
ngk dr8ea vs ngk d8ea
Originally posted by: supersonictoys
The coil generates a certain amount of energy. This energy wants to go somewhere. At a certain voltage the plug fires (regardless of resistance). Until that happens NO CURRENT FLOWS. Whether you have resistance or not does not matter. A paltry 5KOhms does not do anything when compared to the nearly infinite resistance of the gap itself (until the plug fires that is).Once the plug fires the resistance comes into play. The coil cannot get rid of its energy in the shortest possible time due to the resistance.This reduces current flow in the spark and it takes quite a bit longer until the energy in the coil has expelled itself through the resistor. This results in a longer spark. However the spark is slightly weaker due to energy loss in the resistor.
The coil generates a certain amount of energy. This energy wants to go somewhere. At a certain voltage the plug fires (regardless of resistance). Until that happens NO CURRENT FLOWS. Whether you have resistance or not does not matter. A paltry 5KOhms does not do anything when compared to the nearly infinite resistance of the gap itself (until the plug fires that is).Once the plug fires the resistance comes into play. The coil cannot get rid of its energy in the shortest possible time due to the resistance.This reduces current flow in the spark and it takes quite a bit longer until the energy in the coil has expelled itself through the resistor. This results in a longer spark. However the spark is slightly weaker due to energy loss in the resistor.
#12
02-15-2007, 08:52 AM
Supersock
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ngk dr8ea vs ngk d8ea
Impedance Matching
The reason to use a resistor spark plug is mainly to reduce radio interference into the environment and to protect the High Voltage electronics from the damaging side effects of reflections of a high frequency, high-power situation. The most common place we observe the effects of line reflections is in every day cable TV splitters. If we have a television set connected to one side, and an unused split connection on the other (open-circuit), under worst case circumstances, the television set will display a garbled picture. The reason for this is analagous to throwing rock in a perfectly still pond. When the rock hits the water, waves ripple in a spherical pattern; throw another rock in the pond and you will get overlapping waves. In an electronics sense, you have ruined the information being sent and risk sending a more powerful wave back to the transmitter and other receivers in the chain. This phenomenon is called an impedance mismatch. If a resistance, 220 ohms in the case of televisions, is inserted in parallel to all the other circuits, it will channel all the unused energy at a split into useful work instead of wasting power in the environment. Thus, the resistor will prevent the picture from degrading.
Resistor Plugs
In our previous example, we were shown the effect of reflections on a television, now we look at the spark plug. Using a normal spark plug without a parallel resistance, we render all personal communications equipment useless. The reflections from the spark plug produce unwanted harmonics that interfere with any radio equipment you may have. Okay so what do we do? The magic number is 5000 ohms (or 5k) as 5k ohms is roughly matched to the characteristic impedance of the ignition transformer. If we put a 5kohms resistor inside the spark plug or the plug cap, the resistance will balance the transmission circuit and provide maximum energy to the spark plug's anode. Since there will be much less unused energy, the circuit will release much less electromagnetic and radio radiation. The end result is that we get a more efficient spark and less radio interference. The problem with the integration of a resistor is that it is designed for newer ignition transformers. Some find that their bike will just die once enough carbon collects on the center electrode. NGK even warns people on their site about the complications associated with older ignition systems.
The reason to use a resistor spark plug is mainly to reduce radio interference into the environment and to protect the High Voltage electronics from the damaging side effects of reflections of a high frequency, high-power situation. The most common place we observe the effects of line reflections is in every day cable TV splitters. If we have a television set connected to one side, and an unused split connection on the other (open-circuit), under worst case circumstances, the television set will display a garbled picture. The reason for this is analagous to throwing rock in a perfectly still pond. When the rock hits the water, waves ripple in a spherical pattern; throw another rock in the pond and you will get overlapping waves. In an electronics sense, you have ruined the information being sent and risk sending a more powerful wave back to the transmitter and other receivers in the chain. This phenomenon is called an impedance mismatch. If a resistance, 220 ohms in the case of televisions, is inserted in parallel to all the other circuits, it will channel all the unused energy at a split into useful work instead of wasting power in the environment. Thus, the resistor will prevent the picture from degrading.
Resistor Plugs
In our previous example, we were shown the effect of reflections on a television, now we look at the spark plug. Using a normal spark plug without a parallel resistance, we render all personal communications equipment useless. The reflections from the spark plug produce unwanted harmonics that interfere with any radio equipment you may have. Okay so what do we do? The magic number is 5000 ohms (or 5k) as 5k ohms is roughly matched to the characteristic impedance of the ignition transformer. If we put a 5kohms resistor inside the spark plug or the plug cap, the resistance will balance the transmission circuit and provide maximum energy to the spark plug's anode. Since there will be much less unused energy, the circuit will release much less electromagnetic and radio radiation. The end result is that we get a more efficient spark and less radio interference. The problem with the integration of a resistor is that it is designed for newer ignition transformers. Some find that their bike will just die once enough carbon collects on the center electrode. NGK even warns people on their site about the complications associated with older ignition systems.
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