Originally Posted by
DOMIT
Hmmm... am I wrong in the understanding that a "hotter" plug is actually longer for more compression, (igniting the mixture sooner) and a "colder" plug shorter? (related to how far into the combustion chamber it protrudes?) That was always my understanding of how that works... but maybe I'm mistaken? IF that is correct, then the next colder OS plug probably protrudes the same amount as the GRP??? Just food for thought.
Glowplug temp is detemined by the size or thickness of the wire. The hot glowplugs have thinner wires, so they glow very easily, as where the cold plugs have a thicker wire, that requires more compression, heat or lean mixture to get them going. Thats why the cold plugs idle erratic, but come on hard on the mid to topend, due to the RPM's keeping the heat going on the wire.
Novarossi changed up the system with hot and cold in the same heat range. This is the length of the glowplug body, not the wire size. The difference is how quickly it dissipates heat, but will have the same wire thickness in the same heat range.