Re: Difference is Heat Range

Oh yea, just to make things more interesting, an 8 in brand 'A' may not be the same as an 8 in brand 'B'. It is not inconceivable that some manufacturers 'hot' 8 may be the same as another's cold '9'. There is a lot of mutual product testing done to enable manufacturers to create cross-brand conversion tables, however this only suggests one manufacuter's plug is the "nearest equivalent" to another brand - not necessarily identical!! This is predominantly a marketing thing done to slide into a high volume market such as an engine manufacturer's posted requirements, etc.

Ain't life simple?

The number indicates the heat range of the plug...8 being cooler (shorter insulating nose) than 9 (longer insulating nose). Operating temperatures cooler than 850�F tends to promote carbon build-up and hotter than 1550�F tends to promote breakdown of the metal. At about 1700�F the metal will begin to glow and pre-ignition becomes likely. So the ideal plug will be hotter than 850�F at idle and cooler than 1550�F at wide open throttle.
Not to excuse the dealer's goof up, but the difference between the 8 and 9 heat ranges will not likely cause problems...you may simply have an increased carbon buildup. Check your old plugs for the heat range used and look for any indication of carbon fouling or overheating to determine which heat range is best for your particular engine / driving style combination...cooler plugs may in fact be better. Occasionaly pull a few of the new ones (preferrably the easily accessed ones) and see if carbon buildup exists with the colder range and change if required.

Hope this helps,
'88 750iL

If the F8LCRs are the wrong plugs then that is a joke. I will have to trade the car in for an NSX.
I can't own a car that the dealer is not able to fix properly. BMW may have won the F1 race today, Way to go Ralf!, but the service dept. is about a light year behind Honda.
BMW will not get a good recommendation from me and the local dealer will get a zero on the customer satisfaction. Doesn't matter that the car is fixed because I did everything I could to ensure the right parts are used by asking which plugs are right. The parts people said F9LCRs. I asked if they were in stock and they said Yes.
If anyone knows if the two plugs are compatible please respond.

Carl

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