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BYD builds fastest car

autotrader.co.uk

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Re: BYD builds fastest car

#71

Post by privatelypublic »

eptcyka wrote: post #11
nostrademons wrote: post #8

Earlier quoted context omitted.

At that speed the limiting factor likely moves from raw power output to things like cornering ability on the track, grip of the tires, aerodynamics, downforce, driver skill, mechanical linkages, etc. There's a reason why all the world's land speed records since the 1930s [1] get set at the Bonneville Salt Flats or similar flat desert terrain. FWIW, the speed listed in this article was exceeded in 1937. The hard part…

For a top speed run, cornering ability is next to useless. You need grip to put down the power and be stable at speed, the corners taken for top speed runs are fairly wide. The bigger issue here is for how long can a BEV sustain max power output - it can deplete its battery in 2 minutes. EVs also can only produce top power whilst battery is at top voltage, since draining it drops voltage, max power drops with charge…

I'll need evidence of "Top power at Top Voltage." Since so little capacity is at that part of the curve, It'd make sense to design around (as in avoid, not feature) it rather than use it.

I suspect theres inductance and capacitance enough that even if the motors can't handle the voltage, it can be "clipped" until the pack comes down. (Especially since fmu these are 3phase AC motors, the motor driver is already regulating voltage and current to produce whatever the optimal waveform is)

Re: BYD builds fastest car

#72

Post by vjvjvjvjghv »

potato3732842 wrote: post #66
chakintosh wrote: post #26

Earlier quoted context omitted.

This is why the Ring is the absolute benchmark of how well rounded a car is.

>of how well rounded a car is. For performance applications. None of these cars are great daily drivers.

That's not the point of the Nordschleife :-)

Re: BYD builds fastest car

#73

Post by vjvjvjvjghv »

lossolo wrote: post #56
jansan wrote: post #19

Earlier quoted context omitted.

Seven minutes for the Nordschleife? Sabine Schmitz could have done that with a van. But honestly, ther are a Lot of production cars that went considerably faster. And the non-production Porsche 919 Hybrid EVO did it in 5:19, which is an entirely different league.

> Porsche 919 Hybrid EVO did it in 5:19 If anyone hasn't seen this, I highly recommend it, even if you're not a car fan. https://www.youtube.com/watch?v=PQmSUHhP3ug

That just looks unreal. I wonder if this is reaching the point where a driver can't keep up anymore.

Re: BYD builds fastest car

#74

Post by twilo »

vjvjvjvjghv wrote: post #73
lossolo wrote: post #56

Earlier quoted context omitted.

> Porsche 919 Hybrid EVO did it in 5:19 If anyone hasn't seen this, I highly recommend it, even if you're not a car fan. https://www.youtube.com/watch?v=PQmSUHhP3ug

That just looks unreal. I wonder if this is reaching the point where a driver can't keep up anymore.

They can do better

Re: BYD builds fastest car

#76

Post by brianwawok »

privatelypublic wrote: post #71
eptcyka wrote: post #11

Earlier quoted context omitted.

For a top speed run, cornering ability is next to useless. You need grip to put down the power and be stable at speed, the corners taken for top speed runs are fairly wide. The bigger issue here is for how long can a BEV sustain max power output - it can deplete its battery in 2 minutes. EVs also can only produce top power whilst battery is at top voltage, since draining it drops voltage, max power drops with charge…

I'll need evidence of "Top power at Top Voltage." Since so little capacity is at that part of the curve, It'd make sense to design around (as in avoid, not feature) it rather than use it. I suspect theres inductance and capacitance enough that even if the motors can't handle the voltage, it can be "clipped" until the pack comes down. (Especially since fmu these are 3phase AC motors, the motor driver is already regula…

Well you can see reports of people drag stripping teslas, and comparing speeds at 100 vs 90 vs 50% charge. Whatever the reason, you do slow down.

Re: BYD builds fastest car

#77

Post by jakeinspace »

3000 hp? Not sure if that's measured at the "crank" or the dynamo, but that's over 2MW, probably pushing 2.5MW of power draw from the batteries assuming a motor efficiency of 90% and some other losses. Apparently that's getting drawn at 1.2kV from the batteries, so "only" around 2kA of current draw.

That top power draw would drain the 80kWh batteries in around 2 minutes, though I'm guessing you'd hit thermal throttling or catastrophic failure before that. The batteries are allegedly rated to 30C, meaning 2 minutes to full discharge at max current.

I'm curious how the heat dissipation of EVs compares to ICE vehicles. You have much higher efficiency vs combustion and get to split the power between 4 motors instead of one engine, but you don't get the heat capacity of a massive engine block, or the convection of cold air intake + hot exhaust out the tailpipe.

Re: BYD builds fastest car

#78

Post by est »

jakeinspace wrote: post #77

3000 hp? Not sure if that's measured at the "crank" or the dynamo, but that's over 2MW, probably pushing 2.5MW of power draw from the batteries assuming a motor efficiency of 90% and some other losses. Apparently that's getting drawn at 1.2kV from the batteries, so "only" around 2kA of current draw. That top power draw would drain the 80kWh batteries in around 2 minutes, though I'm guessing you'd hit thermal throttli…

> how the heat dissipation of EVs compares to ICE vehicles

Xiaomi Su7 Ultra had a 400W twin fan, 530W liquid pump and a 28kW heat dissipation for powertrain.

Re: BYD builds fastest car

#79

Post by potato3732842 »

vjvjvjvjghv wrote: post #72
potato3732842 wrote: post #66

Earlier quoted context omitted.

>of how well rounded a car is. For performance applications. None of these cars are great daily drivers.

That's not the point of the Nordschleife :-)

A lot of the cars for which lap times are an marketable feature are at least decent daily drivers.

These are not those cars though.

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