MaskedRacerX
Member
Outstanding! Another 10th or two on your 60' and you'd be pushing very low 11s.
Is it worth running in track mode just for the additional cooling?
Is it worth running in track mode just for the additional cooling?
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Finally hit the 1/4 mile with my 21P
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whisperingshad
Active Member
on the track it is irrelevant, plenty of people have tried slip, track mode, and sport mode with almost no difference at all, and sometimes track mode being slower.
Nope. It does not mean that Sam. It means that you're getting into field weakening at high RPM which is an intrinsic feature of most electric motors as they enter their upper RPM bands - that's why you see torque dropping off so significantly (torque output declines faster than RPM rate yielding a net overall power decline past the power peak that is significant) – this is why the cars outside of the Plaid accelerate so much more poorly in the higher speed ranges compared to their amazing acceleration from about 30 to 50 which is centered around the power Peak. This is why it took a motor redesign in the Plaid to maintain power output all the way to the top RPM range of the electric motor such that torque only declines in proportion to rpm.. The motor on the other hand in the model 3 does not have that redesign. Be nice to get that at some point! Although the curves below do not show the model 3 Performance Motor, I believe the higher RPM slopes of the power curves for all these motors outside the Plaid are about the same.
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Nope. You'll actually see your times drop as the battery gets somewhat warmer. Only if you're tracking the car do you want to take heat out of the battery and particularly out of the motors. But for a brief Sprint in a quarter mile the extra heat actually helps the battery pack generates slightly more kilowatts.
MasterC17
Active Member
As @dfwatt mentioned, the power curve falling off on the Model 3 is due to back-EMF. I don't know exactly what they did on the Plaid to get such incredible consistency, since no one else has come even close, but I imagine part of it (beyond of course hardware improvements) is that they could push more power in the middle of the curve if they wanted, but opted for a flat curve instead. Which, with 1,000hp is plenty enough anyway.
Even at 99f ideally you would want pack temperatures even hotter. 120+ would likely yield some (very minor) improvements. For an EV it's best to have a hot battery and cool drive units for drag racing.
Even at 99f ideally you would want pack temperatures even hotter. 120+ would likely yield some (very minor) improvements. For an EV it's best to have a hot battery and cool drive units for drag racing.
You're referring to overall power output, I'm talking about the individual motors. both the front and rear motors go down in a retraction that is identical in shape but at different vehicle speeds. the rear motor does it around 45, and the front motor starts at roughly 55. If in a generic sense, what you are suggesting is occurring, the plateau or retard of power would be reflected at similar points on the chart.
I'm not sure where you got the information Sam that the motor output is somehow being artificially tapered down. Please supply sources for these highly unusual claims. And the front and rear motors have different technologies. The front motor is induction based and the rear motor is switched permanent magnets. I suspect the induction motor may have a slightly higher RPM at which field weakening becomes significant or the gearing between the two Drive systems is slightly different. In any case,. Please consult white papers on this which are available. The other problem for your argument is why in the world would Tesla intentionally limit their top-of-the-line model in terms of its power output? They clearly do inverter limiting of a software nature for the dual motor cars that are not performance models, but even there what's actually trimmed is the lower RPM output torque. They go into the same field weakening/power limiting at high RPM that the performance motors show.
They are without question. Whether that is because of battery constraint, or motor restraint, they are definitely not close to following the chart of a slow decline. Here's an old chart from last year showing how fast the torque drops (still looking for the kW logs). The rear motor is in green, and it loses around 50% torque in less than 2 seconds. The front motor is in yellow, and it loses around 50% torque in 2 seconds but on a plot 1 second further out than the rear.
This is the type of data you see with a VFD controlling power going into a motor, which means that they are being 'tuned' to a lower power level for whatever reason Tesla is doing it.
Since you have such great affection for your misconceptions I'm going to let other members of The Forum try to educate you about this
If you know then please educate me. But my obtuse understanding of what's happening here is that the VFD or VFD-style device is manipulating the motors. Is this not correct?
Screw the "acronyms
I feel the same way. From a dead stop, there's definitly a soft spot. From a slight roll, like you said. Violent.
I haven't tried, but my limited understanding of performance EV's is you want the batteries warmed up pretty good for a 1/4 mile run. Track mode would defeat this mentality I assume by turning on the battery cooling system.
But yes, bein able to hit a 1.5x 60ft would bring it right down to a low 11 run. Problem is, once you get into that 1.5 range... Inferior driveline components such as axles can start showing there ugly head. No idea how much the m3 axles can take. But I would be happy to find out
Permanent magnet switched reluctance motors have something called torque ripple if full power is applied at zero RPM. That's why more power is applied if the car is rolling just a couple of miles an hour. Since a lot of people on this thread appear to be skeptical about established facts if someone is skeptical just look it up
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Almost all cars are like this. One of the reasons that manufacturers measures your to 60 using a 1-ft roll out.
Intervention
Member
I saw a .01 reduction in 60ft with slip start. But thats very negligable
Candleflame
Active Member
Fundamentally these cars are all the same i.e. My 2019 Model 3 AWDPWPP (the official designation for the stealth model 3 in Australia - AWD Performance without performance package) haha.
So I just came home from work and made the switch from "hold" to "creep" and did a few quick 30 jabs. I dunno if it's just me, but the car hits harder off launch with creep engaged. I'm gonna measure my 0-60s over the next few days and see if there's a measurable differance. Wondering if the brake bein applied while in hold at a stop affects launch from 0.
Do me a favour and do a few hits tomorrow with the car in "creep", let me know if it hits harder than launching from "hold"
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