Pmag BR8EIX Iridium Electrode life?

I have been using the NGK BR8ES plugs and replacing them every year. I would like to try the Iridium plugs and I have a couple of questions:

1. Do they last more than 1 year?

2. What should the gap be? They seem to be .030 out of the box.

Thanks in advance,

I've been using the BR9EIX for some time now and in most of my customers aircraft as well, they easily outlast the ES by about 2x from what I see on average. Yes gap is .030 out the box, if the gap goes to .035 I toss them but generally I just toss them at around 150-200 hrs regardless of gap.

Thanks

Thanks Walt,

I'll leave the gap at 030 and monitor for wear.

One more question. I have seen the BR9 recommended for high compression engines and the BR8 for lower compression. I have an IO320 with 8.5 pistons.

What symptoms would lead to choosing one over the other?

I prefer to run the cooler BR9, plug colors look good and no signs of fouling when I remove them. I promote lean operations which drive the temps up a bit hence my preference for the 9

The last time I talked to Brad at EmagAir about spark plugs, he said -8ES or 8EIX, both are good. He also said regardless of what you use, change them every 100-125 hours. Dan from Reno

Walt said:

I prefer to run the cooler BR9, plug colors look good and no signs of fouling when I remove them. I promote lean operations which drive the temps up a bit hence my preference for the 9

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I've never given any thought to the plug heat rating in re: running LOP. I run BR8ESs. Except for take off and landing, I run LOP 95+% of the time and always see nice cool CHTs between 345-380, depending on the air temp. In that scenario, how would a cooler plug affect combustion and/or fouling? My elementary reasoning would tell me that a cooler plug might marginally lengthen the power pulse (due to additional time to burn the charge), resulting in very marginal (maybe too small to tell) additional CHT cooling but higher EGTs, due to the longer time it takes to burn the charge. Does this make any sense?

A cooler plug won't have any affect on timing or spark duration. It just has a longer insulator over the center electrode. The plug runs cooler because it has less exposure to hot gases. A cooler plug may, under certain circumstances, not be hot enough to keep the lead in the fuel in a gaseous state allowing it to condense in the well of the plug and eventually foul. A plug that is too hot could lead to detonation and, potentially, pre-ignition.

If your CHTs are nominal and your plugs are not fouling, stick with the heat range that you have in there now. If you are lead fouling plugs, first try leaning the engine as much as it will take for idle and taxi and see if that prevents fouling. Don't forget to enrichen for takeoff.

Ed Holyoke

Mark Dickens said:

I've never given any thought to the plug heat rating in re: running LOP. I run BR8ESs. Except for take off and landing, I run LOP 95+% of the time and always see nice cool CHTs between 345-380, depending on the air temp. In that scenario, how would a cooler plug affect combustion and/or fouling? My elementary reasoning would tell me that a cooler plug might marginally lengthen the power pulse (due to additional time to burn the charge), resulting in very marginal (maybe too small to tell) additional CHT cooling but higher EGTs, due to the longer time it takes to burn the charge. Does this make any sense?

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