If you REALLY want to read the plug you need to do the following...

1) Make a full pass and click it off at the finish.
2) Tow it back and pull all 8 plugs out.


Trying to read fuel from plugs that have been at anything else but WOT can be misleading.

You CAN read timing from a plug that's been idled afterwards though because the idle temp is much lower then the WOT temp, so the cadmium on the NGK's won't burn back any further.

Those plugs look like they have a touch too much timing in them, but keep in mind that the timing "mark" can be different for any given motor for any given plug range.

As an example I ran a -10 plug on my iron headed turbo car last year. 9:1 compression at 20psi. What's funny is that when it "caved" in the pistons (too much power/heat for a off the shelf slug), the timing mark was just BARELY showing on the tip (no signs of detonation either). What that tells me is if you have too cold of a plug in it, you can fool yourself into trying to read timing from the plug.

What the pictures of your plug do tell me is that you have more then enough octane for what you're running (lots of timing shown on the strap, without any detonation signs).

Not to say I ignore the plugs, but now I read the plug for signs of problems (burn too far on the electrode (excessive timing), and or signs of detonation), but mainly I tune off 1/8mph.

I try not to tune off 1/4mph because it's well above the peak TQ RPM by that point. If you keep tuning for high RPM (1/4 mile MPH), you can hurt the motor with too much timing through the mid range. If it's going to detonate... it's going to do it at peak TQ.

I approach tuning my Turbo car like this.

1) Start low on boost with conservative timing.

2) Get the fuel right.

3) Conservatively rough in the timing. Add some and watch the 1/8mph. Best 1/8mph timing minus 2~4 at this boost level. This will give you a pretty good idea how much deg/boost you need to pull out for a safe attempt at more boost.

4) Add boost and make sure that the fuel still looks good.

5) ONLY THEN add timing.

Sounds like you skipped right to step 5... lol I would take a bit of timing out of it. Tune the fuel until you get the 1/8mph optimized, then sneak the timing back in it.

In this case you've been very lucky that you have enough octane to cover the boost/compression/timing you've tried. On a more aggressive setup the tuning window can be MUCH smaller.

Good luck with the tuning, hope some of that helped you!