Fuel Prime Percent vs spark plug type?

[Kkuzmicki14]

I've been using Iridium IX spark plugs and I have been very happy with their performance especially at idle, low load operation, and cold startup. I have particularly noticed that these spark plugs seem to need significantly less fuel enrichment during cold startup, as well as cranking fuel needed to start when cold compared to traditional plugs. Does anyone have any experience with whether these plugs have a tendency to prefer a high or low Fuel Prime Percent (the single extra pulse of fuel shot when cranking begins)?

[Danny Cabral]

I use those NGK Iridium IX spark plugs too (BKR6EIX #6418 N/A, BKR8EIX #2668 N2O). They're the best spark plugs I've ever used.

FYI: Iridium spark plugs conduct electricity better and require less voltage to fire the spark. Iridium spark plugs are also 6 times harder, 8 times stronger and have a 1200°F higher melting point than platinum. Iridium spark plugs are great for small HP shots of nitrous oxide, however, not for heavy N2O use due to their fine wire design.
https://hosting.photobucket.com/imag...unds&crop=fill (Spark Plug Material Properties)
http://documents.holley.com/techlibr...ech_info_2.pdf (NOS Technical Information - See page 6 for N2O spark plug heat range, ignition timing & fuel octane.)

NGK IX Iridium Series plugs were designed specifically for the performance enthusiast. Fine wire center electrode ensures high durability and a consistently stable spark. Iridium alloy has an extremely high melting point, perfect for today's high-tech, high performance engines.

• Trivalent metal plating provides superior anti-corrosion and anti-seizing properties.
• Corrugated ribs prevent flashover.
• Pure alumina silicate ceramic insulator, provides superior strength and better heat transfer.
• Copper core aids in heat removal.
• Triple seals prevent leakage.

[Kkuzmicki14]

@Danny Cabral: Yes! I've been using the 2668s (1600 HP, 15 psi boost, 93 octane at continuous duty). Danny I know that its all experimental, and I've seen your cranking fuel charts for your various builds, but out of curiosity what have you been using for your Fuel Prime Percent with your builds that use the iridium plugs?

[Danny Cabral]

...but out of curiosity what have you been using for your Fuel Prime Percent with your builds that use the iridium plugs?

Fuel Prime Percent - 200%, for my big & small block Fords.
http://forums.holley.com/showthread....7913#post77913 (Related Cranking/Startup Tuning Post)

@Danny Cabral: Yes! I've been using the 2668s (1600 HP, 15 psi boost, 93 octane at continuous duty).

That's impressive for a fine wire (center electrode) type spark plug.