Since I have datalogged that the computer gives you a little more timing advance when leaning out the air/fuel ratio, I was wondering if I should try and lean the car out more.

What would be a "safe" O2 voltage to run at WOT? Currently I am tuned to run at 0.87-0.88V at WOT in 3rd gear (that O2 voltage is technically the approxomate air/fuel ratio where a regular internal combustion engine on "normal" gas should make the most power).

There should be a point where the power gained from some extra timing advance is negated by running the wrong air/fuel ratio, or I will start knocking and the timing will pull anyway (or I start to risk engine damage). I wonder if more power can be safely gained from leaning out some more.

Any opinions/advice/experience with this?

your ecu advances the timing when the mixture leans out? that's weird.. seems kinda backasswards to me :)

I've head like .78 is about where you would start to notice detonation... I wouldn't push it down that far though. If you really want to find out get some wideband O2 dyno tuning done. I think eventually I'll do this, I went with Greg for Hujjat's Dyno, now I just want to see mine up there. And compair your data logs to the dyno runs and see what the good voltage is for 12.5:1 air/fuel ratio.

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yea, I could use some dyno time, and once I get a few more mods on, then I'll really need to get the car tuned properly

So far I am aiming for about 12.5 or 12.7 to 1, which "should" be about 0.87V on a normal O2 sensor, but as we know that can vary as each O2 sensor is a bit different, and a normal automotove O2 sensor isn't that accurate at that air/fuel ratio

tomorrow I might try a bit leaner while monitoring O2 voltage, but I doubt I'll go down much more than another -2% at 7000 rpms

so, does leaning out increase compression?

No...leaning out is less fuel per amount of air.

yes, i knew that much i was just wondering what he meant when he said he was aiming for 12.5 to 12.7 to 1.

heh heh, wasn't clear there

12.5 to 1, air to fuel ratio