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OK, OK. We spent all day on the dyno, playing with the plugs and tuning changes. Bottom line first, we saw no gains in horsepower or torque. That's not to say we won't, just may require more tuning to use the differences in combustion we saw with these plugs.
We most assuredly saw that the plugs made a difference!
First, on an in-car wideband with stock plugs it was tuned for a flat 13:1 A/F. With no changes in tuning, just install the pulstars, the A/F went to a flat 13.2:1. Why did it go leaner? Best guess and feeling of the Pulstar team is that we were getting more complete combustion, giving less residual O2 in the exhaust. This is what the Pulstar plugs were designed to give, and probably better gas mileage. Any WOT horsepower gains would be a bonus.
The second thing we saw was increased knock retard. Why is a little more complicated. I'll try my best on this one. When you increase the voltage of the spark you get faster ionization of the air in the gap, and get a spark sooner than with lower voltage. A faster spark ignites the mixture sooner and is just the same as adding timing, so for this finely tuned motor, with as much advance as it wanted, now we had too much.
Long story short, with tuning on the A/F, and adjusting the plug gap (60 thousands Vs. 40 stock) we got it back to very little KR, and a flat 13:1 A/F and the same HP and TQ curves as we came in with.
Why the big gain on nmcoyote and no gain here? Best answer I can give is nmcoyote was stock, this was a heavily massaged and tuned vehicle. When you add these plugs you will end up a little leaner and with more spark advance, just what a tuner does to gain power. This vehicle came in with the A/F and advance curve already optimized, so no gain in HP, but time will tell if it gets better mileage.
Sorry if a stepped on Vettepartz toes, he'll post up charts and all gory details.
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