After looking at all the pistons and consulting with several experts it looks like #8 burned up do to running lean and detination. Unfortunately, this lean condition was not detected by the Wide Band O2 sensors. The wide band sensor is installed in the header collector and it measures an average across all four cylinders on the right side of the motor. For now I’m planning to leave the wide band installed for overall monitoring.

For tuning and to prevent this type of issue in the future we’re going to install EGT (Exhaust Gas Temperature) probes in all the header primaries. Then we can use the temperature reading to determine how the individual cylinders are performing and adjust them individually.