Spark Breakdown: Ignition Delay

Our engineers started with the flame kernel that is started when a spark is initially created in the cylinder's combustion area. Once this event occurs, the compressed mixture has to be ignited by contact with the flame front initiated by the spark, an increase in cylinder pressure and/or an increase in temperature. For perfect combustion to occur, all of the compressed fuel mixture would have burned at the point where the piston created a constant volume inside the cylinder. In reality, we recognize that there is always a delay between the initiating spark, flame kernel growth and movement of the flame front throughout the combustion space.

Better Conductive Heat Transfer

Immediately following the spark event in the combustion zone, a critical flame kernel is formed. To ignite the residual gases before the exhaust event, an engine is designed to increase the temperature of the remaining gases, raise the cylinder pressure and expose the unburned mixture to the flame front. We quickly realized a larger kernel is exponentially effective because it offers more mechanisms for heat transfer. Since the larger ball of the flame has more surface area, the conductive heat transfer to the unburned gases is greater. A larger flame impacts the convective heat transfer by tumbling the remaining mixture exposed to radiant heat transfer.

Improved "Mass Fraction Burned"

This means that just a slight increase in flame kernel strength can cause a cascading improvement in the entire combustion process. By getting the flame process started earlier, the mass fraction burned at any given crank angle position away from TDC is increased. Since the exhaust valve opening occurs at a fixed point in the crankshaft's position, we understood how important it is to get as much of the fuel burned before it is vented off during the exhaust cycle. To increase power and reduce emissions, we created an electrode design that burns more of the existing air-fuel mixture in the combustion chamber. E3 Spark Plugs are "Born to Burn".

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