[hansj3]

lately i have been surfing the internet to find general mods, applicable to all makes and models that are in the (or close to) realm of hens teeth. my friend has a 4 cyl wrangler that we have modded for better power and econ. we did the 4.0 throttle body swap and the duratec injector swap and he is getting 22-23 on the highway.... anyway back to the point, i have been looking at ignition tweaks other than the standard indexing and gap expatiation and i came across an article that compared how heat ranges other than factory could be beneficial (albeit in circle track racing). anyway here it is

Heat Range Selection – there are basically two theories on choosing a plug’s heat range for an engine and the tuning that goes with it.
1. Choose as hot a plug as possible – this choice has been the approach for many years and is justified by the thought that you eliminate any low RPM fouling and stumble, and that the hotter plug will light the flame faster at all RPM resulting in a increased burn rate. Advocates of this idea don’t mind cooling the plug by adding more fuel, (richening the engine), and decreasing timing for the race. Most of the supporters of this theory are drag racers, where fuel economy isn’t so important and a slight denotation can be caught before any damage is done.
2. Choose as cold a plug as possible – this is a fairly new idea but is gaining a lot of popularity among the oval track and road racers. The approach here is to run a cold plug coupled with a lean mixture and sometimes an increase in timing. This choice eliminates the possibility of the plug limiting the air/fuel ratio and ignition timing by becoming a pre-ignition point thereby allowing the tuner the ability to find “best power” in both of these cases. Some reports are that fuel mixtures much leaner, and timing higher than previously thought possible have been run with success. This can be a benefit where fuel economy is an issue. Other benefits to the colder plug are that it is more sensitive to tuning changes as not so much of the fuel is burnt off by the insulator heat, also with the increase in compression ratios and subsequently cylinder pressures the colder plugs have provided some insurance against pre-ignition/denotation and are probably much more in-line with the proper heat range for the cylinder temps. In my opinion the only concern with this approach would be in the low RPM situation where there could be the possibility of misfires. However most of the racing done today is at a relatively high RPM and most racers could probably use a cooler plug with no ill effects and the possibility of some benefits, just be sure you have enough ignition.

my thoughts are that it may actually work, and a hotter range or projected plug may be of benefit on vehicles with ecu controlled timing advance and air fuel ratio....and a hotter plug is only good for a 70c jump in plug temp, many vehicles could take up to two steps of heat range before tip temps become an issue.

also thoughts on expanding the gap on finewire precious metal plugs for a larger spark kernel? all the literature i have read states that plugs like ngk G power plugs take less voltage to light off, i was thinking maybe a 6-8 thou over stock jump may help economy
thoughts?