Cadillac XLR tuning LH2 Tune 5d Piston Protection AFR

The default XLR programming includes 0.5 AFR richer tuning at 6000 RPM to cool the pistons.  Ideally there would be a timer associated with it — say after 10 min at 6000 RPM it added — but there is not.  For this tune I removed that variable in order to study the impact from 6000-6400.  Since  there were few other changes in the tune we are focused on the 6000-6400 RPM range.

Specific Changes in Tune 5D:

  • raise piston protection rpm to 8192
  • reduce IAT retard
  • point advance reductions around 5400 rpm to eliminate slight KR

XLR Tune 5D test 1

The blue line is today’s test.  The red line is Tune 5B in hotter weather.  From 6000 to 6500 rpm the Blue line goes up 4 whp from 224 whp to 228 whp instead of staying flat as in prior tests.

The Virtual Dyno test results always seem muted in cooler air, which is counter intuitive.  I wonder if there are other factors such as the air pressure in the tires (reduced in cooler weather) which are impacting the test results.

XLR Tune 5D test 1

The calculated hp in HP VCM Scanner showed a peak of 316 hp.

XLR Tune 5D test 1 peak torque

The calculated peak torque was 308 lb ft.

Overall I was glad to see a positive impact from 6000-6800 rpm and no knock retard.  I am uncertain why cooler weather tests seem to record lower results.  My intuition is there is a variable I am not controlling for.

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