Category Archives: Site Info / News

#Cadillac XLR LH2 V8 Tuning – Tune 9B #Tuning #VirtualDyno

Posted on by
Reply

Tune 9B removes IAT multipliers below 6000 RPM from Tune 9A to keep them from causing KR.

XLR Tune 9B and design for tune 10

Tune 9B tests ran almost no KR, so removing the IAT adders helped there.  The totals were good at 317-320 2nd gear HP.

XLR Tune 9B VirtualDyno with 9A

Both 9B runs were pretty wavey but overall 9B made at least as much WHP as 9A.

In the first graph it is clear that Tune 9B is running MORE timing than the MBT table.  For Tune 10 I am zeroing out PE/COT timing adder and touching up the base timing to pull timing down to the MBT timing shown in gold.

Cadillac XLR LH2 V8 Tuning – More Tune 9a

Posted on by
Reply

Tonight I had cooler weather so I re-tested Tune 9a for baseline comparison.

XLR Tune 9A2 Comparison Calc HP

The 9A2 runs showed some KR spikes at 4150 rpm and 5000 RPM. This appears to relate to a high IAT advance multiplier at those RPMs, which I will zero out for Tune 9B.

XLR Tune 9a2 to 9a comparison

The Virtual Dyno for 9a2 was equivalent to 9a1, which is good news (same tune, different day).

Tune 9B will also reapply the MAF 2% touch up around 8,000 hz since there are some signs of running lean there.

XLR Tune 9A2-0139 HPTuners

The issue of KR due to multiplied IAT advance at lower temps could be why the XLR has consistently run better at high temps (which is counter-intuitive). In the next tune I will change the multipliers below 6000 RPM/below 104F for IAT advance to 0. The alternative would be to zero out IAT advance adders at cooler temps, but there may be some value in keeping them at higher RPMs.

Because the KR doesn’t go up at higher RPM it may be false knock?

Cadillac XLR LH2 V8 Tuning – Tune 9A OEM VVT plus less adv high

Posted on by
Reply

Tune 9A goes back to OEM VVT Tuning, and pulls 2 degrees of advance near redline where combined timing was above MBT.  Timing elsewhere was returned to OEM. KR attack and decay were modified.  Unfortunately for comparison today’s test was much warmer than yesterday’s test conditions.

XLR Tune 9A-0304 comparison to 8A calc hp

Even corrected the hotter weather today drove ~2 degrees of IAT and ETC delta timing.  Ignoring that difference however, restoring VVT appears to have restored the torque dip at 4800, and looks better above 6400.  Tune 9A ‘solved’ the KR issue as well, which perhaps was coincident with the VVT changes?

XLR Tune 9a-0304 Vdyno Comparison with 8A-0942

Virtual dyno was equivalent between 9A and 8A, although 9A has a lot less timing.  This seems consistent with the delivered torque/hp corrected.

Next I would like to see some 9A data under the same conditions as 8A.