hi there fellow forum fellows
been doing lots of data logging on a Holden SS VE and getting a feel for timing requirements, fuel trims, and knock sensitivity and burst knock sensitivity and have found some interesting stuff that I would like to pass on.
As we all know torque is in the timing, mostly, and the good ol factory tunes in the LS1 were average at best. With the Holden SS VE I found that it felt flat over 3000rpm at full throttle and the initial impression was one of disappointment.

Logging showed 4 to 5 degrees knock retard occuring at 3000rpm on the button leaving the rest of the fun behind. Taking advantage of the multi cylinder knock sensor logging I discovered cylinder B ( hopefully not "B" for BOMB ) was the culprit. All the others logged "0". None the less knock retard retards total timing by 4 to 5 degrees.
Timing was a retarded 12 degrees at full load at 3000rpm with the octane scalar right around at 1 due to all the "knocking" . The car made 194 kw , dyno dynamics, at the wheels on 91 octane gas. Timing at peak torque was 14 degrees (4500rpm) with no knock showing. Timing at 6000rpm was 16 degrees.
Experience and logic says, to me anyway, that if it runs 14 degrees at peak torque with no knock, that it should be able to run at least 14 degrees at 3000rpm if not more. Time to investigate Cylinder B knock sensitivity. Gave it a tweak at the 2800 and 3125rpm points, a couple of test drives and hey presto no knock at 3000rpm. The sensitivity was much more trigger happy than the other cylinder knock maps. Could be a random calibration problem, could be that the cylinder B was more prone to knock during testing > not sure but I doubt it.

Octane scalar learned closer to "0" and the car ran another 2 degrees under full load with NO knock registering anywhere on any cylinder.
The car now pulls hard pass 3000rpm right up to 6000rpm and is much more impressive to drive. During all this I was also tweaking the low & high octane timing map downward by up to 10 degrees in places !!! to stop real knock with all 8 cylinders triggering knock retard. The car was on 91 afterall. The octane scaler self adjusts during these changes and I was keeping an eye on it.
I also tweaked the low MAF calibrations by 2 to 4 % to bring long term trims down from 8% at worst to 0 to 2%. PE was also lowered accordingly as the AFR dropped out to 10.5:1 in the top end on the dyno.

I'm now ready to throw it on the dyno again to see if my seat of the pants dyno reads as well as the dyno dynamics dyno. It certainly feels way better on the road so I'm sure I'll see a good result. We shall see.
Then for some real tuning to find the timing limits on 91 octane with these engines. Will keep you posted.

Just incase this reads wrong to people I don't tune cars by looking at knock sensor readings and adjusting timing for no knock. I use minimum effective timing for peak tractive effort. Its interesting to note that the factory PCM is actually set up to do exactly that > look at knock and adjust timing until there is no knock

Its just that this was a new engine to me and new PCM and its easier making observations while on the road driving in real conditions and making some basic changes and observing response etc etc

Mike