Tag Archives: Testing

Improving a tenth at a time…

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100F out today here in Texas, but testing must go on.  Mostly because inquiring minds want to know and my interest is piqued about how this could be simpler and yet any more subtle in execution.

Speed vs Time (red) and Distance Travelled (gray)

 

And the table with comparison to last best run:

Today’s Test
Rollout Previous Test
Speed (mph) Time(s) Dist(f) 0.37 Speed (mph) Time(s) Dist(f)
10 0.93 6.33 0.56 10 0.71 7.13
20 1.71 23.73 1.34 20 1.45 23.53
30 2.53 53.59 2.16 30 2.23 51.94
40 3.43 100.4 3.06 40 3.09 96.6
50 4.45 168.07 4.08 50 4.21 170.2
60 5.66 265.64 5.29 60 5.39 265.8

Conditions: Weather: 95.6F baro 28.85 in Fuel: almost empty (car indicated 100F outside; 96F per the weather underground)

Today I wanted to try accelerating briskly until 20 mph or so then wide open throttle.  My goal was to get to 20 mph as rapidly as possible without wheelspin, figuring that even with full throttle there would be little wheel spin after 20 mph.  I was partially correct.

I also discovered that there is a cusp wherein the 6speed automatic will shift from 1 to 2 early in the low 20s if you are not at wide open throttle, which is bad for acceleration.  Manually shifting the automatic is right out because the redline at 1st comes up too fast for the manual shift to be effective.

Good news is a slightly faster best time, at 5.29 sec 0-60 with rollout.  Remember our goal is 4.9 sec 0-60 with rollout.  Low on fuel so 84 lbs lighter this run, which can also cause this difference in 0-60 times vs the earlier test.  The hotter temps act against acceleration, and 20F hotter is significant.

This simple method did improve my 1 foot acceleration time from 0.59 to 0.37 so there is that.  Also my 60′ time from a dismal 2.8 to 2.66 sec.  A reasonable 60′ time for street car on street tires is under 2.2 sec, so I am off in the first 60 ft and its me not the V.

I do think that this will be a matter of defining an exact technique to get the last few 0.1’s out however — brisk but not tire screeching acceleration up to 18-20 mph then full throttle before the transmission can decide to downshift to 2nd or similar.

In the real world it doesn’t matter much, but learning to drive the car can’t but help.

Intake update: the Spectre intakes are due from Streetsideauto.com in the next week or two, and then we’ll get before and after dyno tests run at True Street Motorsports in McKinney Texas per my  Project Cadillac Tuning Plan

Cadillac STS-V First PerformanceBox Test

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I have a RaceLogic PerformanceBox which can be used to measure vehicle performance in a variety of tests.  The Performancebox is a GPS based meter and data logger.

Unfortunately, I don’t get to use it all the time, so when I do there is a short period of re-familiarization.  For my first tests, no data got written to the memory card.  After I changed the setup to “yes, please write data” things improved dramatically.

Here was the best run written to the card today:

MPH vs Distance shows challenge getting off the line

 

Accel results
Speed(mph)     Time(s)
0-60                   05.4

With 1 ft roll-out details:

Speed(mph) Time(s) Dist(f)
0 0.00 0
10 0.71 7.13
20 1.45 23.53
30 2.23 51.94
40 3.09 96.6
50 4.21 170.2
60 5.39 265.8

Roll-out is a determination for ‘when’ the test time begins.  At a drag strip, there is up to 1 foot of roll-out before the timing lights are tripped, hence the term.  In other words, due to surface quality and wheel-spin it took me 0.59 sec to get 1 foot forward, but at the track that time would not have been included in the results and is not included above.

Weather Conditions: 87F; barometric pressure 29.69 in; humidity 64%.  Fuel: Full

Not sparkling time for the Cadillac STS-V, which Cadillac measured at 4.9 sec 0-60 mph with roll-out.  Most magazine tests ran high 4.x to low 5.x sec.  Road & Track measured 4.7 sec 0-60 mph for the STS-V.

I feel the 2008 STS-V is capable of a better time.  Getting the STS-V off the line involves a great threat of wheel-spin to be avoided.  Of course, my test area is not a sticky well prepared launch spot like at the drag-strip, but it does closely model real world circumstances.

On the bright side, this is a new ‘best’ for my personal vehicle measurements; my previous best was 0-60 in 5.95 sec in my modified CTS 3.6L and was measured on the AP-22 meter in more favorable circumstances.

Stock
STS-V


Mod CTS 3.6L
Speed (mph) Time(s) Dist(f) Time(s) Dist(f)
10 0.71 7.13 0.68 4
20 1.45 23.53 1.40 21
30 2.23 51.94 2.33 55
40 3.09 96.6 3.31 105
50 4.21 170.2 4.55 187
60 5.39 265.8 5.95 301

A line by line comparison — albeit of apples and oranges since different days, different gadgets — echoes the same issue — get the STS-V off the line faster and it would have much better times, and at 60 mph is 35 feet ahead of the CTS.

Tuned Cadillac DTS Performance Sedan sets a new fast time

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TexasJim and I got together today to re-test his 2006 Cadillac DTS Performance Sedan.  TexasJim has had it tuned with EFILive.

Texas Jim's 06 DTS and Bruce's 05 CTS

Texas Jim's 06 DTS and Bruce's 05 CTS

We used a Race Technology AP-22 performance meter (other AP-22 Tests) for the acceleration testing, a CruiseCam headrest camera mount and Kodak C875 Digital Camera for the chase-car video and photos.

AP-22 in the DTS

AP-22 in the DTS

Here was the previous test, with only the best run captured in detail.

Previous Test Best Run

Speed
Seconds
10 0.86
20 1.76
30 2.83
40 3.83
50 5.00
60 6.68
70 8.36

The other recorded run from Test 1 was 0-60 in 7.2 sec.  Using 4,330 lbs, the AP-22 calculated hp at the wheels on run 2 of 238hp, and run 3 of 241hp.  Average whp = 239 whp; 239/0.8 = 299 net hp.

TexasJim's 2006 DTS Performance Sedan

TexasJim's 2006 DTS Performance Sedan

And here are today’s results:

Test 2 Run 2 (Best Run)
Speed Seconds
10 0.89
20 1.70
30 2.84
40 3.86
50 5.06
60 6.55
70 8.25
80 10.18
90 12.53
271 whp / 80% = 339 net hp
Test 2 Run 3
Speed Seconds
10 0.88
20 1.80
30 2.87
40 3.92
50 5.16
60 6.67
70 8.44
80 10.48
90 13.00
269 whp / 0.8 = 336 net hp
Test 2 Run 4
Speed Seconds
10 0.9
20 1.81
30 2.88
40 3.90
50 5.15
60 6.66
70 8.38
80 10.37
90 12.79
263 whp / 0.8  = 328.7 net hp

Conclusion: TexasJim’s DTS previously ran 0-60 in 6.68-7.2 seconds. For the 2nd test (today) it ran 0-60 in 6.55 sec – 6.67 sec. This appears to be an improvement in 0-60 time on average.   Measured wheel horsepower increased from 239 whp average to 268 whp average, or 29 whp.  Having the DTS performance tuned yields positive results.

Caddyinfo Forum discussion thread here.

Cadillac DTS and Cadillac CTS Rear-view

Cadillac DTS and Cadillac CTS Rear-view