I've been tuning my track 2001 Z06 for a while now and have it to where it runs pretty well within what I thought I was supposed to be doing. The tune I inherited was knocking like crazy. I would drop the spark down each time I found knocking. I have ended up with a fairly safe tune that only has 19 degrees of advance when flying full throttle at high speed. The difference in speed and how hard the car pulls during a full throttle straight is greatly noticed from when I first inherited the car. Originally my high spark table was 25 degrees advance in the full throttle 100mph + ranges. Now I've subdued the knocking, but my car is much slower.
I've been researching a bit and have come to find that 25 degrees should be easy for my LS6 engine at full throttle. The 6 degrees I've lowered is giving up a ton of speed and the engine still knocks a bit. I'm thinking either something is mechanically wrong, or I'm ignorant about some tuning process.
I've attached a couple screen shots showing that when I get on it full throttle coming out of a turn, I sometimes trigger knock. Actual and Commanded AFR are pretty close. Sometimes .2 lean. The LTFtrims also concur that I'm pretty close as they are usually kicking in only 2-4% more gas.
One piece of info to consider is that my 01 LS6 suffers from the infamous ring flutter problem where the scraper ring allows some oil up into the chamber. I sometimes get black flagged for smoke upon decelleration coming out of a high speed straight because of this. I also have to keep adding oil (about 1.5 quarts over 2 days and 100 laps)
I've also recently ran some carbon buildup cleaner through my engine.
What causes knock? from my research, running lean, hot spots from carbon build up. How about burned up valves? Oil in the combustion?
Well, I don't seem to be running very lean if at all. My engine is old and I have already done the carbon cleaner (bg44 I think). I recently had my car compression checked and all cylinders were with 7 pounds of each other. Very consistent compression, so reason to believe my valves are ok.
All in all, I need to get the car pulling @ almost 25 degrees like they are supposed to and knock free.
Tune, Log, pics attached. Your help greatly appreciated. Don't worry about offending me. Just educate me and I'll take it humbly.