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Comment by gsnedders | Hacker News Reader

Chiron is traction limited for most of its run; I presume to beat the Chiron's time the Tesla Roadster has better tyres for initial grip.

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Very unlikely. With power you weight beyond useful (this has basically been "solved" since the day someone built a cat around a ww2 military aircraft piston engine), acceleration is determined by aerodynamics (drag and downpressure), tires and the time spent shifting gears. It's pretty evident where Tesla has the advantage.

Shifting gears? Why does it have an advantage?

Teslas don't need gears since they use electric motors. So there is literally no time spent shifting gears.

See https://www.quora.com/Why-don%E2%80%99t-Tesla-cars-need-a-ge...

The original Veyron could change gears in 8ms, and will, IIRC hit 60 in 2nd. Changing gear isn't going to be a considerable part of the time here.

Wikipedia https://en.wikipedia.org/wiki/Bugatti_Veyron states that the original Veyron gearbox could change gears in 150ms, so it is a considerable part of the time.

While the gear are shifting the engine RPM must go down then up; the 8ms figure certainly doesn't account for the complete sequence.

The Veyron does 70 in first gear. I don't know if its 0-60 times require a gear change or not.

Tangent: please don't downvote someone asking questions, people. I for one had not considered that electric motors have no gears to shift, and wondered "surely both cars are automatic? Does Tesla have a patent on a faster automatic transmission or something?" so I appreciated someone asked.

The basic idea is that it is wasting time. But this is no longer a factor as the gear change is instantaneous with Automatic GearBox.

Electric cars do not have a gearbox and just have one rotor. This does place them in a disadvantage when starting though as there acceleration is affected. Formula E cars, have started using a 3 gearbox for their cars in order to have a faster start.

So it is possible that the Roadster does have a gearbox.

Tesla tried a gearbox in the first Roadsters, and it didn't go so well.

Tesla may have a better traction-control algorithm. Or the electric motors may make it easier to modulate power more rapidly/precisely (vs gas).

The 2nd picture on this page is interesting: https://electronics.stackexchange.com/questions/271674/tesla...

I don't think you're right about this. If the 60-0 time and the 0-60 time are the same for the Chiron then it's limited by traction (assuming brakes that are strong enough to break traction at 60).

Most high performance cars only shift once before 60, and with modern dual clutch transmissions it only costs a fraction of a second.

The only way Tesla are going to get below 2 seconds is either with non-street legal tyres (cheating!) or some new tyres that nobody else has.

Their demo car uses Pilot Sport Cup 2 tires, which are also used on the Buggati Chiron and Koenigsegg Agera RS (which recently set two records for fastest 0-400kph-0 and fastest production car road speed). These tires are street legal.

The Roadster is significantly faster than other supercars from 0-60 on the same tires, so the advantage must come from much more efficient anti-wheel slipping from the three electric motors coupled to AWD. This dramatic speed advantage is probably a result of the ability to quickly alter the power output per wheel to minimize efficiency losses from breaking traction.

FWIW, all of the hypercars on the market have custom compounds, so the fact they're both called "Pilot Sport Cup 2" by Michelin doesn't really matter all too much.

Braking has a very different load distribution, even with a center of mass as low as in supercars. I would not put to much into that comparison. Tires are depicted as Michelin in the announcement, it would be very surprising if they keep their best exclusive to Tesla, considering the relative proximity between Bugatti and Michelin, the relative cheapness of the Tesla and Volkswagen group representing a much bigger part of the tires market than Tesla for the foreseeable future.

> it only costs a fraction of a second

In other words: exactly the scale of the differences we are talking about. In addition to the short interruption itself I guess that it also takes a few millis until traction control has settled after a shift.

> Chiron is traction limited for most of its run

This sounds very dubious, unless it has negative aerodynamic downforce. Even then, the times for each successive mph drop off too fast for it to be traction limited. Even F1 cars are not traction limited for more than a brief spell of straight-line acceleration. Aero drag dominates very quickly.

Cornering or braking, on the other hand...

The Veyron had little downforce when put into suicide mode, right?

From memory, I remember seeing something claiming that the Chrion's 0–60 and 60–0 times were identical.

That's doubly fishy, since it has an airbrake.

[My caveat on this, I'm not a road-car enthusiast, so I'm just deducing. But I used to work in motor racing, mostly bikes. Based on the standard of reporting I saw about stuff I did know well, I don't trust the motor press on tech claims.]

Most likely a lot more weight.

Lighter tires as rolling at 400kph+ is not a requirement and a fraction of the interiors

The top speed is quoted as being in excess of 400km/h? They have the same problem with speed rating of the tyres.

I'm also curious as to how much it will weigh given the batteries (given the weight of other Teslas).

one is a real car however, the other a rendering. I don't expect figures to change drastically from the brochure, but still.

The new Roadster is definitely real, not a render. They were driving them around, at speed, and showing off the acceleration, at the announcement!

Doesn’t mean much. They had to replace a lot of stuff between the presented and production model x, like the door hinges, because from prototype to reality there’s an abyss, especially for a car that’s supposed to sustain thise speeds.

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