Discussion in 'Roadster' started by I=V/R, Aug 9, 2009.
I've gathered all of the time slip data I can find from the last two weekends of drag racing. Most of the slips come from this site - many thanks to Tom Saxton for entering his slips into a spreadsheet already!
So far, I've found 35 runs by 2008 Roadsters (Please note: I've eliminated two runs by 2008 Roadsters which appeared to be outliers caused by driver error, leaving 33 runs by 2008 Roadsters), and 7 runs by James' 2010 Roadsters Sport.
Here is a quick analysis of the data so far.
The standard deviations for the 2008 run and for the 2010 Sport runs are very similar. The 2010 Sport advantage comes early, with around a 5% faster time at 60ft, 330ft and over 4% faster at 1/8m. The 2010 Sport advantage is down to 2.6% by the 1/4m because the .35s lead built by 1/8m stays constant from there.
I believe there is an additional outlier in one of the 2008 runs - there is a 60ft time recorded of 1.903s, which is the only 60ft time under 2.05s for any 2008 run. When this value is eliminated, the 60ft best times and diffs match what is expected based on the mean times and diffs.
If you have slips that you have not posted, please post them here so I can add them. I'd especially like to see some 2010 non-Sport slips from this weekend.
RichKae has the 2010 non-Sport. I believe he only did two runs though.
An important variable is the state of charge and the temperature. Also, was the Roadster warmed up or running cold.
I have seen my personal rimes change from 12.82 to 13.06 seconds. And my times are always consistent based on the state the car is in. For example, last Wednesday my times were 13.06, 13.05, 13.03, 13.03, 13.03. There was almost no variation except the car was gradually warming up.
On Friday I had a higher charge level and my times were 12.99, 12.98, 12.97, 12.96. They were gradually getting better as the car warmed up.
The difference between Portland and Seattle conditions is critical. In Portland we could charge in performance mode right in the pits at 240 volts / 40 amps. Also we could run as many times as we wanted and quickly, so the car had a chance to warm up. Portland would represent the ideal situation. I got my best personal time of 12.82 and the record of 12.643 was set under these conditions.
In Seattle we do not have charging at the track and there have been long delays of 1 hour or more between runs. So the car is always cooling down and never really getting into prime 1/4 mile condition.
In general, when I have observed the 2008 vs 2010 Sport head to head races, the Sport is generally about 0.2 to 0.3 seconds faster at the quarter mile when the cars are in the same charge/warm-up condition. Also, I am easily the biggest guy in our group. I am 6'3" and weigh 250 lbs. Most of the other Tesla owners are lean guys below 180 lbs. When Scotty Pollacheck (135 lbs) was in my car, he did 0.2 seconds better than me. So the real difference might be closer to 0.4 seconds.
Also another variable is driver skill during the launch. Tom Saxton is getting good at the launch, whereas whenever I have tried to load the motor during my launch, I mess it up and get a horrible time. I have tried twice now during an official 1/4 mile. I have been practicing a little at stoplights, so I think I have it now. Elon Musk emailed me some advice, but I still have not yet gotten it right when being timed. We will see next time.