I seem to remember once reading a technical paper or something which described the process leading to the development of the 'BUR' series slotted electrode spark plugs for Mazda engines. My impression was that the design had more to do with heat reduction/distribution than any ignition or geometric reason. On the other hand, Yamamoto suggests that the slot is there to facilitate a 'bleed off' of high pressure in the trailing squish flow area of the rotor.

Can anyone remind me where I read this? I assume it must have been an SAE paper or something like that, but I have been looking for it and haven't come up with anything. I know some people on here ( arghx ) have huge libraries of this stuff, hopefully you guys have a better memory or something than I do.

Thanks,
Pat