Nissan also built a bunch of dual plug engines. That was back when they even did it with a distributor. It was mostly for emissions, I thought. Almost all aircraft engines run dual plugs. They have large open combustion chambers and dual plugs helps pevent detonation and get the fire done sooner. Aircraft engines generally test pretty good for specific fuel consumption too considering the antiquated appearance of the combustion chamber designs.
Years ago Champion sold a plug with an auxiliary gap up in the ceramic insulator that allowed the ignition to build to a higher voltage before it fired. This plug should be compared with the old auxilary gap design and then tell us how much better it is. It just looks like too much for too little to me.
edit: I cannot find a description of the Champion plug on the net. Often times pulling the plug wire back from a fouled plug and having it arc to the plug would get the plug to fire.
Speaking of plugs, here is an Idaho invention that has run in quite a few engines, even airplanes. It appears derived from model air plane glow plug technology.
http://www.smartplugs.com/index.html
This started out so promising and now nothing for several years.
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