ignition timing and A/f Options

[ncgalant]

Alright, lets get down to it. I'm looking for power. Given that, which is better, a little richer and more ignition timing, or leaner and less timing? Currently I'm working toward the latter, but want some input from some that run fast.

Also, which is better for spool, lean or rich. I can't get my pre-boost #s into the rich range. If I do a 3rd gear pull from 1500-6500. My O2s will read .08 until 3500 or so when they jump up to .8 and then .9 around 4000. My setup is working, but I want it to be the best it can be. I can post up my SAFC settings if you guys want too. Their F'd up.

[ncgalant]

I don't know that there is any right or wrong way as long as what your doing is safely making power. In my mind and according to my buttometer, the more timing the better, but YMMV. The ECU will start pulling the timing on its own when it gets dangerous because it sees knock. If its not seeing the timing getting actively pulled during a run, the engine's probably not knocking (2G ecu guessing here).

Yes, this is what us OBDII guys have to do. The hardest part is determining the difference from knock and SAFC induced load when watching your timing drop off. When I first started tuning I went through this quite a lot. I would see timing drop 2 or 3 degrees and the more I added the worse it got.

I can't wholly agree with this. More boost begets more fuel. Basically to get more power you are trying to stuff more of both in to the combustion chamber while maintaining a safe yet efficient AFR. Since we have more matter in the chamber altogether its going to take more time for all that matter to burn. Obviously we have less time every stroke as the RPM increases so the timing is going to have to advance to maintain an efficient mixture, lest we start throwing fuel out the tailpipe or even worse leave it in the combustion chamber to detonate or wash the cylinder walls. Now exactly how much the timing needs to advance, I don't know. The 5 to 10 degrees of advance may be what works well for the guys on pump gas since it burns more quickly than race gas anyway.

I was more talking about your dynamic compression ration causing a faster burn rate. I can surely see what you mean though. If there's more air and fuel to burn that has to take longer to do it. So we can probably figure the actual burn rate is somewhere in between.

I think what I'm going to try for is running a bit more boost and seeing if I can keep my timing right where it is(17 degrees up top). All of this will be limited by knock of course. It curtainly makes sense that if the charge has more time to burn, then it would burn more completely and make more power with what you have.