Quote:
Originally Posted by wwest
If one were to use one of the newer ignition coils with both HV ends available, both plugs MUST fire since they are in series, a single MSD could be used. That is provided the capacitor charge were in the range of 600(Bosch)-900(MSD) volts, since in this case both plugs would be firing during a compresion stroke.
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If anything over 9.5:1 CR and 95mm+ cylinder bores in a Porsche 911 engine requires twin plugs to prevent / control detonation, how would one live without detonation with only one box if your statement is true about only one plug firing? Mine leads a very happy, detonation free life with very hard driving for a street engine. It's 10.5:1 CR with twin plugs driven by one MSD 6AL.
IF BOTH PLUGS WERE NOT FIRING THE ENGINE WOULD DESTROY ITSELF. PERIOD. I have pulled the upper and lower plug leads on #1, attached two plugs and grounded them to the engine case. I started the engine, and although it ran a little rough on five cylinders, and clearly observed both plugs firing. Not only were they firing, they were firing bright blue. When I revved the engine the spark becomes constant to my eye, but both plugs fire all the way up to 6500 rpm. How does one account for that if they are both not firing?