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14mm spark plug choices

Planecrazy232

Planecrazy232

Well Known Member
I have a Lightspeed III ignition and have been using Denso (5312) IK27 plugs. I noticed the NGK BR8ES being used by other electronic ignitions. The NGK are much less expensive. Are these the same heat range and acceptable to use with the Lightspeed? The Densos are the only ones listed on the Lightspeed website.
 
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Planecrazy232 said:
I have a Lightspeed III ignition and have been using Denso (5312) IK27 plugs. I noticed the Bosch BR8ES being used by other electronic ignitions. The Bosch are much less expensive. Are these the same heat range and acceptable to use with the Lightspeed? The Densos are the only ones listed on the Lightspeed website.
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I think you mean NGK, not Bosch. I did a lot of experimenting with NGK and several Denso variants in both 9.7:1 O-320 and a 9.3:1 IO-360 and LSE ignitions, and came to the same conclusion as Klaus the Denso's were worth the premium. Denso's can be ordered at a significant discount through Kragen/O'Reilly auto parts.
 
deek said:
I think you mean NGK, not Bosch. I did a lot of experimenting with NGK and several Denso variants in both 9.7:1 O-320 and a 9.3:1 IO-360 and LSE ignitions, and came to the same conclusion as Klaus the Denso's were worth the premium. Denso's can be ordered at a significant discount through Kragen/O'Reilly auto parts.
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Corrected Ngk/Bosch.
 
This is a little bit of apples and oranges comparison. The Denso 5312 is an iridium plug, while the BR8ES is a common copper-core plug. The better comparison would be the NGK BR8EIX.
 
14 mm Spark Plug Choices

Planecrazy232 said:
I have a Lightspeed III ignition and have been using Denso (5312) IK27 plugs. I noticed the NGK BR8ES being used by other electronic ignitions. The NGK are much less expensive. Are these the same heat range and acceptable to use with the Lightspeed? The Densos are the only ones listed on the Lightspeed website.
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Iridium plugs are generally more expensive than standard nickel plugs.

No, the IK27 are not the same heat range as the NGK BR8ES. According to various internet charts the Denso heat range 27 is equivalent to NGK heat range 9 (one heat range cooler than the BR8ES).

According to Sparkplugs.com specifications the IK27 is an Iridium projected electrode plug with more costly NGK equivalent BKR9EIX iridium projected electrode plug. Also the IK27 hex size is smaller than the BR8ES.

The NGK BR8ES lower cost DENSO equivalent is cross referenced to W24ES-U.

Lightspeed may consider the DENSO one cooler heat range, iridium electrode, extended electrode plug to be better for their application than the NGK one heat range hotter, nickel electrode, non-projected electrode used by others.
 
Running one P-Mag

Am having trouble deciding on plugs.
Is the consensus to use NGK Br8EIX?
Do they run hot or cool?
Having cooling issues and working on jetting and timing changes....
Bought some on Amazon for $6.50 each and got nervous about fakes so sent them back.
 
Have a look at NGK BKR9EIX (stock # 2669), solid terminal.

They are middle heat range (comparable to Denso IK27).

I’ve been running with them for 100’s hours with dual LSE Plasma III on my 8.7:1 equipped IO-360-A1B6.
 
Heat Range

Also: Am running 9.5:1 and having cooling issues to resolve.
How would this affect "heat range" choice of plugs...??
Thank you.
 
flyingriki said:
Also: Am running 9.5:1 and having cooling issues to resolve.
How would this affect "heat range" choice of plugs...??
Thank you.
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Generally you want a plug to run hot enough to burn off deposits, but not so hot that it glows and causes pre ignition. CHTs have almost no bearing on this (very little correlation with combustion temps), but CR does. It is the combustion chamber temps that the plug is matched to. If the majority of the 8.5:1 engine run an 8 plug, I would run one # cooler with 9.5:1, but have no idea if that is necessary. Higher CRs create higher combustion temps. You can "read" a plug to see if it is too cool, too hot or just right. Clean off the neg electrode and look for the heat signature line. With an optimum heat range for that engine, the heat signature line will be mid-way across the perpendicular section of the electrode. FInding the optimum heat range requires sophisticated instruments. The method I mentioned is what the hot rodders do when modifying engines. Not perfect, but good enough to be safe.
 
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flyingriki said:
Also: Am running 9.5:1 and having cooling issues to resolve.
How would this affect "heat range" choice of plugs...??
Thank you.
Click to expand...

Check your timing -- for 9.5:1 CR you should be ~19° BTDC vs the "stock" 8.5:1 at 25° BTDC.
 
I have a lot of experience with BR8ES vs BR8EiX plugs in snowmobiles and dirt bikes over the last couple of decades. In two-stroke engines the main advantage of the EiX plugs is less of a tendency to foul. I found that to be irrelevant in 4 stroke snowmobiles and motorcycles. In my airplane (dual eMags), I believe that the only benefit of the iridium plugs is longevity. I change plugs at every condition inspection anyway, so AFAIK zero advantage to the BR-8EiX plugs in an airplane.
 
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