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Tips & Tricks
The BR9EIX Iridium plug:
The Iridium-coated central electrode of the "I" model does not burn away like the steel standard plug's does (the "S" model).
Furthermore, the "X" denotes a Booster Gap which delivers a stronger spark (this is part of what pushes the price up. plus of course the cost of the iridium coating, which is a platinum compound)
The central electrode has quite a sharp point which helps develop a cleaner, more concentrated spark for better combustion.
Note that the temperature range of the plug does NOT change the operating temperature of the engine. It is the just the temperature of the central electrode! The plug must get hot enough to burn itself clean at normal cruising power (especially after a long idle where it tends to foul up). It must not get so hot that the central electrode burns away. Steel burns in the presence of oxygen at high temperatures. Iridium can handle MUCH higher temperatures.
So if you normallly use a B10ES or BR10ES, then drop down to a 9 (one step hotter) when you change to iridium. (e.g. BR9EIX).
In very cold climes, you can drop another number, to an even "hotter" plug, e.g. to an 8 in the above example.
Once you use an iridium plug, you will probably never go back to standard steel plugs again, except in emergencies when your favourite plug is not available.
If you do not want to spend to much on an iridium plug, then try the premium Platinum plug "Denoted by a "P" after the number.
So, how are the NGK type plugs named?
e.g. NGK's BR9EIX
B = Thread diameter and pitch (yes, there are other dimater plugs!)
R = Resister, i.e. the RF Noise Supressor (to reduce noise on your radio)
Number = heat range, lower numbers are hotter. This is merely the heat-path along the ceramic surrounding the central electrode. If its deeply cut-away, the heat must travel a longer patch to escape via advection to the cylinder head, so it gets hotter.
E = Extended length thread - to prevent the soft aluminium threads from stripping at high temperatures - Solo210 pilots with tuned exhausts will know all about blowing plugs out of the head in flight due to the standard thread length.
S = Standard Steel. I = Iridium.... and many others. Some denot ethe shape of the side electrodes.
X = Booster Gap for more powerful spark.
Try one, you will never look back again.
Diego offers these for discerning pilots.
Regards, Keith Pickersgill