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

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.

 

Cadillac XLR LH2 V8 Tuning – Tune 8A

Tune 8A commands 12.8:1 AFR from 1500-6700, where Tune 7A was at 12.5:1 AFR.  The VVT in 8A has some minor cleanup in an unused area.   The piston protection in 8A is at 8192; in 7A 6400 rpm.   7A was the ‘just advance the timing’ run, so 8A has 2 degrees less timing from 2300-5600 more or less, with -3 at 4200-4400.

XLR Tune 8A all 5 runs calc

I ran 5 runs today to study run to run variance.  I have started not initiating the scan until ready to test, which avoided (randomly?) the scanner hang issue. The reference number for each test is the Tune (8A), the time the run starts in its scan (0942) and the test area used for the run (A, B, C).  Test area A data was uniformly hard to smooth for Virtual Dyno, so I will plan to exclude it and focus on B or C.

The runs on the graph above are all the same tune 8A.

XLR Tune 8a to 7a calc hp comparison

This comparison of 7A, which was non-viable due to heavy KR, vs 8A-0942C.  Even with the main spark retard in 8A there is still some KR in that run, perhaps caused by IAT advance?

XLR Tune 8A comparison timing to 7A

8A is able to run more timing than 7A partially due to conditions, and due to avoiding some KR at 5000 RPM.  The max timing on 8A actually runs above MBT so I will reduce timing from 6500 RPM. One knock event causes 3 degrees of KR and the characteristic stair-step decay from 4250-5500 rpm.  My goal is to tune out any knock.

These show the raw calculated data, with no smoothing.  All 5 runs HP data, 1 run torque data for reference.  The hp/torque maximums are shown for each run, which is less valuable unsmoothed but provides a reference.

XLR 8A-0942C Virtual Dyno

This is the Virtual Dyno wheel hp / torque for the 8A-0942C.

Here is a comparison across viable runs with a Tune 7A run included

XLR Tune 8A 3 Viable Run Comparison

Given 7A and 8A are on different days they appear to be equivalent and I don’t see a tune delta in the Virtual Dyno plot.

XLR Tune 8A comparison 7a Virtual Dyno

 

Cadillac XLR LH2 V8 Tuning — Tune 6F Retest & Baseline

Tonight’s test was Tune 6F RETEST, a retest of the Tune 6F calibration to help build a baseline for comparison.  For the record, the VCM scanner froze, the XLR tilted, I used the code reader to reset, then the scanner worked properly and I ran the test.

XLR Tune 6F Retest compare with 6F and 6B

Tonight’s run is in BLUE. The comparison, same-calibration 6F is in RED.  The GREEN Tune 6B is the great first test after VVT Tune with the mid-hump.  Both 6F’s have the same tuning in that region.

XLR Tune 6F Retest Weather

Calculator: https://wahiduddin.net/calc/calc_hp_dp.htm

Weather: http://www.srh.noaa.gov/data/obhistory/KDFW.html

This is the calculator I am using to adjust for altitude, humidity, and temp.  Then I feed the dry-air absolute baro and test temp into Virtual Dyno.  This results in a close match :  the dyno correction is 1.058 above; the Virtual Dyno factor from uncorrected to corrected is also 1.058 with these changes for today’s conditions.

XLR Tune 6F RETEST only 6F Retest and 6F

The Tune 6F retest matches well with the Tune 6F test result, which is what we hope to see.  The peak is 4 whp different, but these are identical calibrations on different days.

XLR Tune 6F RETEST hptuners HP Peak

The Calculated hp peak in HP tuners for Tune 6F Retest was 295.7;  corrected that would be 295.7 x 1.058 = 312.9 hp in 2nd gear.  Next will be more runs with this tune to further characterize baseline after the Virtual Dyno profile issue.  What we want to see is when corrected for conditions, repetitive runs of the same tune show very close results.

 

XLR Tune 6F-R comparison with engine dyno

This chart is a comparison of Cadillac’s engine dyno result in red with the corrected calculated hp result from HPTuners in blue.  In my STS-V with a similar transmission the 2nd gear virtual dyno ran 6% less than my chassis dyno.  If that correction is also correct here, it (yellow) overlays the engine dyno plot up to 5400 rpm or so.