Acceleration:
Rob and I did a total of six acceleration runs in alternating directions, although the first two didn't turn out perfectly. :) The first run Rob launched with a reasonable amount of brake-torquing, which resulted in a fair amount of smoky wheelspin. Fun, but a bit slow (a 16.0 second quarter mile.) The run after that got a bit of wheelspin and Rob got out of the throttle very heavily, aborting the run. Clearly, we need more practice! <vbg>
After that Rob dialed into the zone and the remaining four acceleration runs came in between 15.4 and 15.7 seconds at 90-92mph, with 0-60mph times between 7.4 and 8.0 seconds (unadjusted.) Nice work, especially with the Impala having over 66,000 miles! And, of course, it'll only get faster with the upcoming modifications... mwahahahaha!!
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Power:
The Impala SS is rated at 240bhp @ 5200rpm and 280lb-ft of torque @ 3600rpm, and due to the supercharger the powerband is immediate and quite flat/non-peaky. The maximum measured power was 176bhp @ 4800rpm, and 203 lb-ft of torque @ 3700rpm. After using my corrections spreadsheet to correct for temperature, weight, boost, the moon being in the house of Saturn, and the mind-control rays the aliens were using when we made the runs, the adjusted figures are 213 bhp and 246 lb-ft of torque. These are pretty good results, when you factor that it's an auto-tranny, supercharged, front-wheel drive car that I'm trying to magically reverse-calculate power for. When you add in that it's got a few miles on the clock you can see these figures should be in the right neighborhood!
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Technique:
As before, the primary challenge was to avoid vaporizing the tires, especially since Rob is trying to get another full year out of them. HA! HA HA! Anyhoo, after the first run with some brake-torquing resulted in smoke and a half-second slower run than the others, Rob switched to little or no brake-torquing and smoothly rolled on the throttle. You can still see from this comparison of the last four runs G-force that how quickly Rob got on the throttle determined how much traction was available.The runs' RPM variations during launch shows that the Impala was working at the limit of its traction.
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Corrections and Other Factors:
Once again I've corrected the quarter mile results to the weight of a single person, quarter tank of fuel, and SAE J1349 standards. Since this is the first time we've done these corrections on the Impala, and it has 66,000 miles on the engine, it lost a step or two from the tests in 2004:
| Recorded Data | Corrected Data | |
|---|---|---|
| Best run: | 0-1/4 mile in 15.4 secs @ 90 mph | 0-1/4 mile in 15.3 secs @ 91 mph |
The good news is, of course, that the mods should get us a few back! Stay tuned...