NGK Spark Plugs

[John_in_VA]

1 hour ago, fastricky said:

What about NGK Iridium? Any more info/opinions on those?

 

They were the plugs designated for use in the E39 & E46, and that's where I use them.

[elfhearse]

I installed NGK Iridiums prior to the Vintage trip.  I have about 1500 miles on them now, no fouling, look great.   Great price from Rockauto ($5.63 each + shipping)

[airborne85]

try them, you'll (immediately) like them......

 

ira

[BenjaminSmith]

Why wouldn't I want resistor plugs?

[Clevis Woodruff]

Resurrecting an old thread . . .

 

According to NGK, as has already been observed here:

 

"The spark plug heat range has no relationship to the electrical energy transferred through the spark plug. The heat range of a spark plug is the range in which the plug works well thermally. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type."

 

Is it correct to infer from this that a BP5ES would be a hot climate plug, and a BP7ES would be a cold climate plug?

 

If the M10 in question is a low-revving engine connected to a too-quick-to-upshift 3HP12 automatic, and the existing plugs of unknown brand are a little carbon fouled, and we're heading into cooler weather, then would a BP7ES be a better choice than the highly acclaimed BP6ES?

 

[TobyB]

Nah, the heat range refers to how much the electrode protrudes from the porcelain insulator.

 

The body of the plug carries heat off the electrode, so the less tip exposed, the cooler the electrode runs.

 

Think of it as 'preheat'-  too hot and the plug predetonates, too cold and it'll misfire under some circumstances

(often full load, or very lean transition)

 

t

 

[Clevis Woodruff]

Ah, okay.

 

Essentially a "colder" plug (higher number in NGK's numbering) is more insulated against combustion heat, and a "hotter" plug (lower NGK number designation) is less insulated.

 

From NGK's website:

https://www.ngkntk.in/ngk-technology/importance-of-heat-range/

Importance of Heat Range

The heat rating is a measure of the amount of heat dissipation.The heat range of a spark plug is the range in which the plug works well thermally. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type.

Effect of Selecting Wrong Heat Range

1. When the heat rating is too high

The spark plug temperature remains too low and causes deposits to build up on the firing end; the deposits provide an electrical leakage path that gives rise to a reduction of spark.

2. When the heat rating is too low

The spark plug temperature rises too high and induces abnormal combustion (pre-ignition) ; this leads to melting of the spark plug electrode that could cause problems such as piston seizure.