Dizzy question searches but didn't find
07-29-10, 01:03 PM
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Dizzy question searches but didn't find
Could I use a 2g dizzy on my 12a? Since I'm running 2g coils for leading and trailing? My dizzy cap and rotor aren't being used so it would make my engine look a lot better.
07-29-10, 02:54 PM
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the EFI cars have a Crank Angle Sensor. its different than a distributor.
the CAS is similar in construction to a Distributor.
the distributor has 2 magnetic pickups in the body, one for leading and one for trailing.
the shaft has a 4 tooth trigger wheel, so at its 50% engine speed, a tooth passes each pickup every 180 degrees, and the cap and rotor pick the rotor.
the CAS by contrast outputs the engine rpm and position to the ecu, and the ecu decides when to fire the coils. the CAS has 2 trigger wheels, a 2 tooth, and a 28(i think) tooth wheel. the 2 tooth wheel i think mazda calls the G signal, or home, it tells the ECU the engine position. the other is the Ne signal, and after the "home" tooth, the ECU counts teeth to get rpm, and accelerations
the amount of work it would take to get the CAS to act like the dizzy, you'd be better off building a crank trigger thing
the CAS is similar in construction to a Distributor.
the distributor has 2 magnetic pickups in the body, one for leading and one for trailing.
the shaft has a 4 tooth trigger wheel, so at its 50% engine speed, a tooth passes each pickup every 180 degrees, and the cap and rotor pick the rotor.
the CAS by contrast outputs the engine rpm and position to the ecu, and the ecu decides when to fire the coils. the CAS has 2 trigger wheels, a 2 tooth, and a 28(i think) tooth wheel. the 2 tooth wheel i think mazda calls the G signal, or home, it tells the ECU the engine position. the other is the Ne signal, and after the "home" tooth, the ECU counts teeth to get rpm, and accelerations
the amount of work it would take to get the CAS to act like the dizzy, you'd be better off building a crank trigger thing
07-30-10, 11:14 AM
#6
It is not good to run trailing with waisted spark. You need the dizzy rotor button to select the correct rotor to fire. Leading is fine with waisted spark.
A quick Google search gave me this text from rotary engine illustrated that explains it:
"Notice that the "Leading" (lower) plugs fire simultaneously, while the "Trailing" (top) plugs fire independently of each other. The extra spark of the leading plug late in the exhaust stroke is called a "waste spark". Using a waste spark simplifies the ignition system as only one coil and ignition signal are required for both leading plugs. The trailing plugs cannot utilize a waste spark because the timing would ignite the incoming air/fuel mixture in the next chamber."
http://www.rotaryengineillustrated.c...quicktime.html
A quick Google search gave me this text from rotary engine illustrated that explains it:
"Notice that the "Leading" (lower) plugs fire simultaneously, while the "Trailing" (top) plugs fire independently of each other. The extra spark of the leading plug late in the exhaust stroke is called a "waste spark". Using a waste spark simplifies the ignition system as only one coil and ignition signal are required for both leading plugs. The trailing plugs cannot utilize a waste spark because the timing would ignite the incoming air/fuel mixture in the next chamber."
http://www.rotaryengineillustrated.c...quicktime.html
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07-30-10, 05:04 PM
#9
Unless you are using a CAS and computer, like stock second gen, then yes. Running the plug wires directly to the trailing plugs and bypassing the stock "switching" element of the rotor button is a bad idea. Great for leading - not trailing.
Better to run the trailing wires off the cap. Basically the coil still fires twice but the rotor button sends the spark to the correct rotor.
Since you are direct fire on the leading you can use the leading spots on the dizzy cap. One less gap for the spark to jump.
-billy
Better to run the trailing wires off the cap. Basically the coil still fires twice but the rotor button sends the spark to the correct rotor.
Since you are direct fire on the leading you can use the leading spots on the dizzy cap. One less gap for the spark to jump.
-billy
07-30-10, 05:49 PM
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K I'll go back to stock trailing. That must mean that the 2g coil that I was originally using for the leading was going bad cuz I put the 2g coil that I most recently bought and put that on leading and put the old one on the trailing and noticed a pretty significant improvement and my car smelled a lot less of gas fumes. Thanks a lot Billy.
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