Maybe MX5 will weigh back in on the subject. He and Bob Stockum had found that detonation was a problem with turbo and supercharger add-ons and performance enhancements on the 2001 and 2002 models. For that reason, I think it was decided that the #440 was the best choice for higher heat applications.
It was discussed previously that the double platinums would possibly give more area to heat up and cause premature detonation (like dieseling) in high heat apps.
I haven't taken part in any experimentation, other than relaying what I have read in other forums. My GT is now doing a little bucking between 4500 and 5000 RPM under boost; most noticable om the 2nd to 3rd gear shift. It is a 5 speed, and I don't have any place close by to try it at that RPM level on 3rd to 4th shift or higher. I suspect the results would be similar.
I think there was discussion also about using a colder plug, or possibly a shorter reach one.
One aspect that bears some consideration is what happens to the plug wires if the plugs start missing. The wide gap calls for a hotter spark, and the coil assembly(s) are probably capable of delivering higher voltage levels under misfire than the plug wires can consistently handle without breakdown. At some point, plug wire breakdown would have to be factored in, and if overlooked, could add considerable confusion to diagnosing the overall problem.
|