I am wondering what the take is on this considering modern ignition systems do not have the failure rate of older style. Also considering many are using unleaded gas without the lead deposits. I am also wondering about how big of an area a piston would need to have and the speed it would need to be traveling under combustion pressures to actually need two spark plugs igniting to ensure proper flame travel and complete ignition at realistic aviation power levels (that is at what size {generally} would a engine have to be to "need" two spark plugs)?
