Pinging is simultaneous detonation of the entire unburned charge, mostly triggered by the spark (what the knock sensor feels). Normal spark ignition causes a flame front to progress rapidly through the charge. With 100 or more octane, and a 9.3 compression ratio (designed for 91 RON gas), the compression pressure and temp may not rise high enough to trigger detonation, even under boost. So, if the advance is not limited, it may become excessive. I agree that, if there is detonation, the ECU should back the ignition off, unless that function was altered by the chip program.

I can't quite agree with you when you say:

You want your spark to happen such that maximum cylinder pressure occurs right as the piston is starting it's down stroke. If it happens sooner (piston is still on upstroke) it will ping/knock.

Because the flame front takes a finite time to propagate through the charge, ignition must occur before the piston reaches top dead center. How much in advance varies from engine to engine. Usually around 15? for production cars, rarely 30?, for engines that turn 12,000 RPM or more. So, I wonder about the 29? advance in your log of the XR chip. That just seems excessive to me at 6,200 RPM.

When you say:

My test results would seem to agree, as the chip making more timing accelerated faster.

Timing may not have been the only cause for better acceleration. How about more boost?

VonK


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