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Comment by compiler-guy | Hacker News Reader

The level of hubris here is pretty high. "No reason"? "No performance benefit"?

Porsche is spending billions of dollars to bring a very high performance track-focused sports-sedan to the market. Hundreds of extremely good engineers are getting paid millions of dollars to figure this problem out.

I'm sure the transmission is a giant set of engineering tradeoffs (what project isn't), and maybe it won't work out and will end up being the wrong solution.

But it can't be so obvious that random Joe-and-Jane HackerNews know the answer off the top of their heads and Porsche doesn't after all the resources it has spent to figure out the problem.

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So, I'll just hop in here and lay out the spoiler.

There is a major performance difference in the Taycan, it's endurance, and it's highly likely this transmission is a key element to achieving it.

For those that don't know, Tesla's cars can not keep their maximum performance up for a very long time. The battery gets hot and lowers power output until it cools back down. The Taycan, while not having as impressive max specs or range (and some serious questionability about the charging claims) CAN keep its maximum performance indefinitely. At least through a full discharge of the battery pack, but, also after a recharge it can keep going and they demonstrated this recently with a 24 hour marathon test drive stopping only to charge it.

So, without really getting into all the weird perception based arguments, there is clearly a difference in performance and the transmission may be critical to it.

Another reason the Taycan can output near maximum power for a much extended time period is it operates at 800v vs 650v as compared to the Tesla.

Higher voltage alone does not magically give you longer sustained maximum power.

It's also unclear to me why a gearbox alone would give you longer sustained maximum power.

Most electric motors are most efficient and can generate the most power within a certain RPM range. (It's a lot wider than gas engines, but beyond a certain speed the torque falls off.) If you can drive at high speeds at a more efficient motor RPM, then that's less excess heat for the motor and inverter to deal with, and less current draw from the batteries.

Electric motors are pretty much opposite of gasoline engines. Motors have peak torque at 0-2krpm and it drops off rapidly after that. Gasoline cars tend to hit peak torque near the end of their rpm range (ignoring turbos that can change that in any number of ways).

From what I can see, most electric motors are tuned to have peak efficiency at ~5krpm which is conveniently around freeway driving speeds.

One might even imagine they were engineered to be optimally efficient at freeway driving speeds! :D

For single-speed EV’s, the motors are operating very far away from their maximum efficiency point at high speeds. By upshifting, you can reduce the number of revs required at top speed, which should improve efficiency and reduce heating of the motors.

Alone it's probably not enough. In combination with other design decisions, it could be the key though. Take for example the smaller battery. Normally that would be a big limiting factor as battery size is somewhat indicative of maximum power output. But by shifting gears once through the acceleration curve, they can compensate for the lower max power. Furthermore, they could keep higher speeds with less constant power output.

The reason this matters is because a smaller battery will produce less heat overall, which will be easier to cool, and so on.

Anyway it's just a theory. The facts remain: the Taycan can do something the Teslas can't and this gearbox is the biggest single meaningful difference in design of the powertrain. It stands to reason they are related facts to some degree or another.

Higher voltage means less current for the same power. Since the power dissipated on the battery is proportional with the current you want to draw less current. What a lot of people do not understand is that the lack of a gearbox in an electric car is a big problem. When the motor is running suboptimally the excess energy taken from the battery will be transformed in heat.

It depends what speeds make the motor run sub-optimally for a particular vehicle. The range 0-80 MPH is sufficient for almost all normal driving. If you want to make an efficient track car that can operate at high speeds optimally by all means introduce a gearbox. Its going to add more weight, complexity and maintenance though. I don’t think thats the target for any of Tesla’s cars besides the 2020 roadster though.

This is more of a function of battery chemistry on the S/X - the Model 3 does not have the same power restriction under load.

Which makes Elon's promise of sending the Model S round the ring a bit confusing.

Presumably it would be a suicide run to match the Taycan, which to my understanding would involve modifications and not be eligible for the same category.

Either it was an idle boast, or we're about to see the launch of the 21700 Model S.

The new raven model S has the same battery chemistry as model 3

It does not. Raven altered the motor and suspension, battery is same as it ever was for MS (18650) M3 uses 27100, which is taller so can’t just be dropped into the current MS

Not 100% accurate. It is a new battery pack but still based on the 18650 cells. Tesla battery packs have a numerical code which was incremented for the packs in the raven models.

The most pronounced new feature is the ability to charge at up to 200kW on the new V3 superchargers. M3 can do up to 250kW and non-raven S/X can only do in the low 100s.

Once around the ring is not an issue. It's a day at the track that's a problem, not one lap. And not an issue at all if you're fine with waiting periodically while the battery temp comes back to optimal.

Do you have data for a Tesla completing a single Nurburgring lap at full speed? AFAIK they failed each time so far https://insideevs.com/news/323053/tesla-model-s-fails-to-lap...

You're super 100% wrong. The model 3 absolutely does have the same restriction under load. I have no idea where you're getting your ideas.

I am a Model 3 owner, I assure you it will reduce power after a time. No need to take my word for it though you can find plenty of autobahn demo videos showing it. It's not terrible but it is a thing and it's "worse" with track mode.

Numerous "sporty" car reviews also mention this fact. It's just the way it is. Not an impact to most drivers. Absolutely critical to someone who loves the track.

Super 100% wrong! That’s impressive for a clearly factual statement. It is indisputable that the Model 3 does not have the same power restriction under load, and that is primarily attributed to the new battery chemistry.

That is not to say that the Model 3 is entirely unlimited in its power delivery. But a 2018 S/X will go into a low-power mode before you can even finish one lap on the ring and the Model 3 will not. The stock Model 3 Performance brakes will overheat however.

I’ve watched several videos where Bjørn Nyland pushes his 3P to top speed for sustain periods and does not see any power limiting. He shows the same driving on a Model S which gets power limited.

A cursory Google search finds several Tesla forum threads showing people with 3P not being power limited on the track.

I am also a Model 3 owner, and I’ve never seen it reduce power, but I’ve never driven it faster than 110mph for a few minutes, and don’t take it on the track.

The main issue I’ve read about 3P is that the brakes overheat. It needs carbon ceramics on the track.

It is universally acknowledged that power delivery on the Model 3 is better than S/X.

I understand your sentiment. I'd like to add the fact that the original Tesla was a two-speed, or perhaps it was the original design for the Model S, but they scrapped it for simplicity IIRC.

It was in the roadster, it was dropped due to poor reliability for all future designs.

> But it can't be so obvious that random Joe-and-Jane HackerNews know the answer off the top of their heads and Porsche doesn't after all the resources it has spent to figure out the problem.

Does this same discussion-closer apply when we talk about software? Plenty of software companies with the same hundred engineers millions of dollars thing. Yet we are allowed to talk about their fuckups. What makes you think cars are different?

> Porsche is spending billions of dollars to bring a very high performance track-focused sports-sedan to the market. Hundreds of extremely good engineers are getting paid millions of dollars to figure this problem out.

And yet their car is only about as fast as a FWD 300HP Renault Megane RS on the Nurburgring.

I honestly don't understand this. Almost all of us drive at safe speeds on public roads and sit in traffic.

Focusing so much on racing just comes across as a distraction. I love my Model 3, But my older Leaf was fast enough for me.

Then you are absolutely not the target market for any Porsche, let alone this one. Not a dig, I'm not the target market either.

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