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Many have running problems with larger gaps that go away with regapping or new plugs.
US and Canada have RFG fuels that have lower volitility, harder to ignite as well. Perhaps comparisons with experiences with fuels in Europe are a problem. Oxygenated fuels might not be the same thing in Europe either.
You are asking all kinds of questions. Why don't you see what works well for your vehicle?
Yes, Saab coils may be good for 40K, but coils do not last forever. 40K is the poetial for the coil, but the working voltage of the coil is a function of temperature, sharpness, polarity, pressure etc. Coil failure is a function of time, voltage, temperature and vibration. If you choose to increase the gap, and therefore the voltage, the stress on the coils is increased. Does that wider gap improve running and starting? If you cannot demonstrate or preceive any advantage, why do that? And if you start with wider gaps, why have them erode even larger from there.
Larger gaps might work ok for new plugs with sharper edges. (The platinum plugs will have a lifetime sharpness compared to basic plugs.) But large gaps on a mature plug will probably lead to running problems.
If someone states that platinum plugs are not good for high performance mods, its probably because the lack of a thick electrode leads to the end of the center electrode getting too hot. So it might simply be a heat range issue. If the plugs get too hot, this does not mean that platinum plugs are the problem, they simply may be a misapplication for those heat ranges. And whats good in europe at sustained high speed on boost may not have any significance for a modified vehicle that on boost for very short periods of time where after a few seconds speed limits and traffic get you off of boost. The whole issue of thermal performance of a plug resists simple conclusions.
Meanwhile .035" works well and provides a long trouble free in-gap service life.
You seem to be seeking something majic or different about plugs. But once the combustion process is initiated, the plug is out of the picture. Its all really about supporing a short distance, short duration electic arc dicharge. The only other issue is how the DI percieves whats going on with ionization resistance across that gap. That might be gap dependant. But a +10% change in gap is a 10% change in ionization resistance I would expect. But knocking conditions are going to push changes that swamp a 10% variation.
If you are seeking a minor improvement in responsiveness or power for a given boost pressure, then look at boost control and fuels. Perhaps playing with gap changes when the real problem is sub-optimal octane is dealing with the wrong issue.
posted by 65.68.102...
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