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Offline Art

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Re: iridium spark plugs
« Reply #20 on: 22 February, 2020, 12:49:30 PM »
@parbajtor aside from the price difference can you shed any light on the plug type difference in particular the C vs IM and the EHIX vs C in the CR8EHIX-9 and IMR8C-9H plugs?

Or can anyone translate the specification of the IM and C in the IMR8C-9H NGK plug?




Offline Shed

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Re: iridium spark plugs
« Reply #21 on: 22 February, 2020, 08:09:30 PM »
Having trouble sleeping Art?!  :008:

Fill your boots...

https://www.ngk.com/learning-center/article/174/ngk-numbering-systems






Offline Art

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Re: iridium spark plugs
« Reply #22 on: 23 February, 2020, 10:23:09 AM »
I did see that chart but it fell at the 'shell field' with no 'I' coding? Research in favour of sleep I found some more information, the IMR8C-9H coding can be found in NGK's Premium Plug Numbering list. So here's what it all means.

C = M10x1 thread with a 16mm hex fitting
R = Resistor
8 = heat range
EH = 19mm reach, half threaded to 12.7mm
IX = 0.6 fine wire iridium centre electrode, nickel ground electrode
9 = Spark plug gap in mm

I = Premium iridium centre electrode
M = M10x1 thread with a 16mm hex fitting
R = Resistor
8 = heat range
C = Special design construction (possibly that platinum ground electrode)
9 = Spark plug gap in mm
H = Special feature (possibly 19mm reach, half threaded to 12.7mm)

So it appears there is very little difference in the NGK codes for these plugs. So are these plugs interchangeable? Do so at your own risk. For my two penneth I'll replace the CR8EH-9's in my MKI (SC58) at the next valve clearance service, due in 10,000 miles from now, with the CR8EHIX-9 and let them do their stuff for their 50,000 miles of service life. Equally if I had a MKII (SC64) I'd not be replacing the original factory fitted NGK IMR8C-9H until they'd covered their 100,000 mile service life.

Links
https://t.tekniwiki.com/fileadmin/public/Redaktion/Dokumente/PDF/ngk_zuendkerzen_code_en.pdf
https://www.sparkplugs.com/Data/uploads/Charts/NGK_Plug_Chart_1.jpg
https://www.sparkplugs.com/Data/uploads/Charts/NGK_Plug_Chart_2.jpg
https://www.ngk.com/learning-center/article/202/how-long-do-iridium-plugs-last

« Last Edit: 23 February, 2020, 10:29:34 AM by Art »