Designing engines for specific plug metals

[JHZR2]

Hi,

I am curious about engines seeming to do better with one plug brand/metal/type, as compared toothers.

For example, for the 2.0L engine in my mother's plymouth breeze, copper plugs perform much better (in terms of idle smoothness, etc) as compared to platinum plugs. It does better on Champion and NGK plugs than anything else.

Ive heard that for the 4.3L V6 in my S-10 ZR2, that AC Delco plugs do better than anything else, and in the late model ones, tha tthe delco platinums ar ebetter than the rest.

I dont know how true this sort of stuff is, but over many a BB and usenet topic, I tend to read this sort of trend, so I tend to believe it, at least to some extent.

So, I can see if an architecture is different ('v' grooved center electrode, different shape to ground electrode, etc., that there may be some small differences... but other than metal quality, etc. I dont see much of how there can be a huge difference from brand to brand.

So, that takes me to ignition systems... can they be designed to operate better with copper or paltinum plugs? Is such a thing tailorable?

Just trying to get a grasp on why one plug would do better than another in this or that application, either by brand, metal type, etc. It seems to be a consistent trend that each make has a best application spark plug brand/type, and then it goes down... and Im not even talking about gimmick plugs like the splitfire or bosch +4.

Any insight would be appreciated.

Thanks,

JMH

 

[wileyE]

Think it might have more to do with heat range, or heat path up the porcelain. Seen many plugs cross referenced to be of the same heat range that aren't, or at least don't act the same. Don't know if this is intentional or a matter of economy of application? case in point spitfires, one size fits all applications. The metal used means very little in terms of spark energy IMO, .001" of airgap change would be way more difference in conductivity than the difference between copper or unobtainium. Multiple ground electrodes are for 100k mile tuneups and emissions warrantee , a single ground strap may erode the gap open in this time, causing aslight lean misfire at idle (un bunrt gasses). The downside is they may shroud the spark somehwat in the combustion chamber. Apparently not too much a problem because they are being used by the oems.

 

[Eddie]

I have generally found that the best plugs are the same type as origional. That makes sense to me as I suspect that the manufacture tests those plugs in that engine. In my present case the same engine is supplied from the factory with NGK & Denso copper core standard plugs. I've tried Bosch & Champions and found they did not preform as well once the mileage got to about half way to a normal plug change interval. I suspose ones driving style like WOT repeatedly will require a colder than normal plug but, I just replace what came with the vehicle when new.

 

[Whimsey]

Quote:

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I have generally found that the best plugs are the same type as origional. That makes sense to me as I suspect that the manufacture tests those plugs in that engine. In my present case the same engine is supplied from the factory with NGK & Denso copper core standard plugs. I've tried Bosch & Champions and found they did not preform as well once the mileage got to about half way to a normal plug change interval. I suspose ones driving style like WOT repeatedly will require a colder than normal plug but, I just replace what came with the vehicle when new.

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That's been my experience also. Especially with "later" model Ford vehicles, 80's & up. Also my VW's from the 70's through the mid 80's always seemed to perform the best and get the best life from the plugs if I used the factory brand and spec'd plugs.

Whimsey