There are a lot of variables impacting just how much power the motors put out. Let me just outline the several that I know about:I will say that my instinct would have been that @gearchruncher was right and the vehicle is always at it's amp limit. But I'm perfectly willing to concede that's wrong and the governing is more complex than I'd have expected since @Sam1 and others have tested while holding as much constant as they could. I'm not going on a buying spree for rotational mass reductions, but I can load a few hundred pounds of wife and children in the car for the communal scientific goodI've actually just been eyeing the dragy for years.
Edit - sorry I didn't go back and re-read the thread. I may be misattributing things @dfwatt said to @gearchruncher. Whoever said it, my guess would have been the motors/inverters/etc are always operating at a defined peak and that weight reductions would make a difference like any other car, but those with actual data seem to say otherwise, so any interesting situation.
1) your trim level and obviously whether you have dual or single Motors. This is obviously software limited in that the folks with the ghost module have shown that you can take any dual motor car as long as it has a certain type of rear motor and remove the software inverter limit and get the thing to accelerate like a performance model. But it's telling they haven't been able to find any extra power and those guys know their stuff so there is no extra power at least in a safe sense past what the inverters are set at for the performance models.
2) your charge level. This again is obvious but people don't seem to understand that this actually has a big impact on acceleration particularly past about 30 miles an hour. No one's been able to demonstrate that there's any difference however between 90 and 95% or between 90 and 100%.
3) your battery temperature. This is not so obvious and there's no way to index it because without special software that can read info off the can bus there's no way to know what your battery temperature is. But the batteries put out more power when they're warmer and the difference can be significant in terms of several percentage points. This is basic chemistry. Cold batteries conversely don't put out as much power. This I believe explains much of the fictional notion that putting extra weight in the car after an acceleration run doesn't seem to change the acceleration times. The batteries might be warmer and therefore the car is putting out slightly more power and that might compensate for your extra weight.
4) your traction control and vehicle stability system. These have a big impact and even in track mode they're never completely turned off. There's a lot of speculation but not a whole lot of data about whether launch torque is limited or whether in fact the motors are incapable of breaking tires loose on a dry clean surface , which would require about ~1.2 G's of launch force, slightly less in the front and slightly more in the rear due to weight transfer. I suspect that it's the latter (the motors are unable to generate that much torque ) combined with #5, which is probably the least appreciated factor of all.
5) low RPM torque limitations that maybe software or may be firmware instantiated that prevent torque ripple in permanent magnet switched reluctance type motors which is the type of motor in the rear of the car. Induction motors do not have 'torque ripple' and therefore they would not be subject to software throttling in order to prevent it.
There's nothing like the blogosphere to bring out unlimited speculation and then the dissemination of whatever disinformation rumors rise to the top of those speculation bubbles. The problem is no one has ever presented a single shred of data showing that adding or subtracting 100-200-400 lb to the car results in the same acceleration when you account for battery state of charge, battery temperature, and the other variables. There are on the other hand a ton of YouTube videos showing that simply going from very heavy stock wheels to lightweight forged wheels dropping roughly eight to 10 lb a corner shaves at least a tenth of a second off the car's acceleration 0 to 60. This is consistent with the evidence that reciprocating mass is about 4 times more critical in terms of its impact on acceleration then overall vehicle mass.
There is not a single shred of believable data supporting the fiction that the car has its power adjusted according to some g meter that allows the acceleration to remain constant across a bunch of different vehicle weights. When you ask people what their data is, they simply make a claim they can't provide any data because they don't have any. I challenge people like gearcruncher who disagrees with Newtonian mechanics to go run his own dragy test with a car unloaded and then putting 200 pounds of sand bags in the trunk or in the front seat and then retiming the zero to 60 run. I've already done these tests and for every hundred pounds I add I lose about a tenth 0 to 60. I challenge him to produce his own data. Unless he's going to lie he's simply can't produce data that supports this claim.
In science it's data that supports claims . . . . not more claims. Show me the data. This is pure fiction and pure b*******. We already have plenty of evidence that disinformation floats to the top of the blogosphere and gets disseminated as though it's fact. This is just the latest example. Fortunately this kind of disinformation isn't costing people their lives because they're refusing shots that might save their lives because they believe that those shots will cause their sex organs to drop off or that involve lizard DNA or microchips. So it's just b******* but not lethal b*******. I guess that's some kind of progress!
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