Virtual Dyno vs HPTuners Delivered Torque Curve

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Here is an Virtual Dyno analysis of a 2nd gear run up for my STS-V.  The Virtual Dyno considers the change in speed and estimates the hp & torque, much as a regular dyno.  The difference here is that the V is in 2nd gear and pushing against the wind.

2013-05-11 reset hot test

Virtual Dyno makes beautiful dyno graphs; one can get the full size by clicking on the image above, then hit return to return.

Here is the same info for the same run, graphed using the STS-V’s reported delivered torque and calculated hp for that torque, along with the IAT2 temps:

resetruncomparedeliveredhptorque

The Delivered Torque is an estimated value by the V computer based on engine parameters, and is equivalent to an engine dyno as opposed to a chassis dyno as in  Virtual Dyno.

Both show an item of interest and why I was graphing — the peak torque for the V is not up in the 5K’s but is still around 3500 RPM.  Certainly the torque curve is very flat for the supercharged V8.

Somewhat surprising how much the two disagree on the slope of the HP above 6000 RPM.  The transmission is already thinking about shifting to 3rd at that point, which could effect the incremental results measured by the Virtual Dyno more — the engine output doesn’t care if the engine is ‘clutched’ or not.

Do you have any suggestions on how to get more info out of this data?  I am using HPTuners to capture sensor data from a test drive, then saving as a .csv file, and using Virtual Dyno to analyze the .csv, or Calc to create the lower graphic from the .csv data.

 

Cadillac STS-V shift testing, adjustment 1

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[Note the video quality can be adjusted up (click on the gear), and the video can be made full screen.]

Adjustment 1 set: Kept the 1-2 shift at 30 mph, and raised the 2-3 shift to 60 mph across all shift modes.  Raised the absolute fuel cutoff from 6700 rpm to 7000 rpm.  TM adjusted to 25%.

Interestingly, with no change in shift points the 1-2 shift revved to 6600 rpm and hit a new higher calculated hp value.

Shifttest2013-05-11max15

Previously the 2-3 shift was commanded at 58 but happened at 60 mph.  When I moved the commanded mph up to 60 mph it continued to be commanded at 60 mph.  More testing needed there to understand.

I observe that the car is actually slowing down during shifts, perhaps due to engine braking in sport mode.  I will plan to retest with the transmission in drive, which does not use engine braking, to see if that is advantageous.

Update:  I see a source of delay in the 0-60 time — wheelspin after the 1-2 shift is a problem.

Mph Time
0 0
5 0.56
10 0.95
15 1.31
20 1.66
25 1.98
30 2.17
35 2.45
40 3.03
45 3.08
50 3.14
55 3.19
60 5.03
Too much wheel spin after the 1-2 shift at 3 seconds is causing a false mph indicator for a spike to 55 mph after the shift.
The 40-55 run in the middle is due to spinning tires.

run1at15accelerationgraph

Reinstated TM and retested.  Didn’t go WOT early enough in the retest to avoid the transmission shifting early 1-2 (shift commanded at 23 mph).

run1at15accelerationgraph2ReinTM

 

Cadillac STS-V Exact Shift Point Testing

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This morning I made 2 runs to determine current shift points during acceleration from a standing start.

I ran the STS-V in “competition mode”; this mode apparently uses “Cruise mode” shifting, which was a surprise to me but means a different table for the transmission logic.

run1gearshift12

Run 1: From 1st gear the shift to 2nd started at 30 mph as programmed. The STS-V reached 6,180 rpm before shifting.  The shift took 0.2 seconds.  The 2-3 Shift started at 60 mph and the STS-V reached 6,310 rpm before shifting.

HP Tuners Information

HP Tuners Information

Run 2: From 1st gear the shift to 2nd started at 31 mph.  The STS-V reached 6,378 rpm before shifting.  The shift too 0.2 seconds.  The 2-3 shift started at 60 mph and the STS-V reached 6,240 rpm before shifting.  The latter is surprising since the logic appears to command the shift at 58 mph and not 60 mph.

With a goal of raising the shift points to 6600-6800 rpm, my plan is to increase the 1-2 shift speed from 30 mph to 31 mph.  In first gear, 140 rpm equates to 0.6 mph.  So a full mph increase in shift speed may raise the shift point by 230 rpm or so from 6,380 to 6,600 rpm. For second gear, 40 rpm is around 0.6 mph, so 200 rpm increase would be 3 mph, or 58 mph up to 61 mph.

I will plan to retest under similar circumstances to see how the changes effect the actual result.  What do you think?  The model predicts that hitting the proper shift points will produce a slight improvement in acceleration.  Have you done these type of adjustments to your car before?