Stop the Press! Tesla announces REAL HP numbers for P85D and P90L

[vgrinshpun]

There was an interesting question posed here, that god tangled up in some snippiness and moved over to that thread, but it was an interesting question none the less:

If the P85D had been built with the exact same battery and inverter but with motors capable of only 463 hp motor power, instead of the theoretical 691 hp motor power, would the car have performed the same or not?

I actually addressed this question before it was posed up-thread - here.

The short answer is that P85D with 463 motor hp will definitely not perform as well as P85D with 691 motor hp (with both variants having max available battery output of 463 hp). In fact such a car will perform *worth* than P85 and 85D.

The fact that this is even a question now demonstrates how much time was wasted on bickering on these threads, with majority of the participants not understanding and not willing to try to understand the core issue at hand. I am saying this because the technical details allowing to answer this question were laid out more than one time.

 

[sandpiper]

To take things to the logical extreme, I wonder how much it would cost Tesla to install some capacitors and a bit of circuitry that could output enough current to bump up the motor power to 691HP for 10ms? Technically that would meet the 691 peak hp spec although it would do nothing to change the performance of the car.

It's an interesting situation. The P85D has a vastly different power & torque curve than any ICE vehicle. So comparing the peak power of one to the other really is apples and oranges. Peak HP has, historically, been a useful metric only because ICE engines have fairly similar power curves. It really is a useless number when comparing performance of an EV to an ICE.

You almost have a situation analogous to the incandescent / LED lamp ratings. The power consumption of the LED lamp can't be used as a metric for light output because it's so much more efficient than incandescent. So they use an "equivalent" rating that allows people to buy a bulb that meets what they need.

You almost need the same thing with an EV. You need an "ICE equivalent power" rating. Or better yet you need some sort of other, non HP rating that would allow a buyer to correspond the power in an EV to that of an ICE. It would ideally take into consideration the usable maximum power output of the vehicle (including all drivetrain losses) at all points on a maximum acceleration profile.... to some fixed speed. You could do that by simply integrating the power output as the vehicle goes from zero to, say, the legal speed limit.

Of course, there's an easy way to do effectively that that doesn't involve any math. Just take a stopwatch and measure 0-60 performance!

 

[rns-e]

Interesting point of view on the value from torque... looking forward to other thoughts here.

Torque actually do not matter, as it was acceleration and hp Tesla used to advertise its performance and used to compare the P85D to the other models in the design studio. Torque may matter from a technical point of view but not from a contractual.

 

[dsm363]

Interesting point of view on the value from torque... looking forward to other thoughts here.

It's the torque, not hp, that most people love about EVs (not some here obviously). When you punch it at a light and your passenger's head is thrown back against the seat with the EV grin that's where most of the enjoyment comes from. Did people really buy an EV with 1 gear for 80-140mph passing speed?

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To take things to the logical extreme, I wonder how much it would cost Tesla to install some capacitors and a bit of circuitry that could output enough current to bump up the motor power to 691HP for 10ms? Technically that would meet the 691 peak hp spec although it would do nothing to change the performance of the car.

It's an interesting situation. The P85D has a vastly different power & torque curve than any ICE vehicle. So comparing the peak power of one to the other really is apples and oranges. Peak HP has, historically, been a useful metric only because ICE engines have fairly similar power curves. It really is a useless number when comparing performance of an EV to an ICE.

You almost have a situation analogous to the incandescent / LED lamp ratings. The power consumption of the LED lamp can't be used as a metric for light output because it's so much more efficient than incandescent. So they use an "equivalent" rating that allows people to buy a bulb that meets what they need.

You almost need the same thing with an EV. You need an "ICE equivalent power" rating. Or better yet you need some sort of other, non HP rating that would allow a buyer to correspond the power in an EV to that of an ICE. It would ideally take into consideration the usable maximum power output of the vehicle (including all drivetrain losses) at all points on a maximum acceleration profile.... to some fixed speed. You could do that by simply integrating the power output as the vehicle goes from zero to, say, the legal speed limit.

Of course, there's an easy way to do exactly that doesn't involve any math. Just take a stopwatch and measure 0-60 performance!

That would be interesting. 10ms of 691hp would make everyone happy then I guess.

 

[tomas]

Torque actually do not matter, as it was acceleration and hp Tesla used to advertise its performance and used to compare the P85D to the other models in the design studio. Torque may matter from a technical point of view but not from a contractual.

Torque hugely impacts acceleration. C'mon. And what contract are you talking about? Please attach it.

 

[rns-e]

To take things to the logical extreme, I wonder how much it would cost Tesla to install some capacitors and a bit of circuitry that could output enough current to bump up the motor power to 691HP for 10ms? Technically that would meet the 691 peak hp spec although it would do nothing to change the performance of the car.

It's an interesting situation. The P85D has a vastly different power & torque curve than any ICE vehicle. So comparing the peak power of one to the other really is apples and oranges. Peak HP has, historically, been a useful metric only because ICE engines have fairly similar power curves. It really is a useless number when comparing performance of an EV to an ICE.

You almost have a situation analogous to the incandescent / LED lamp ratings. The power consumption of the LED lamp can't be used as a metric for light output because it's so much more efficient than incandescent. So they use an "equivalent" rating that allows people to buy a bulb that meets what they need.

You almost need the same thing with an EV. You need an "ICE equivalent power" rating. Or better yet you need some sort of other, non HP rating that would allow a buyer to correspond the power in an EV to that of an ICE. It would ideally take into consideration the usable maximum power output of the vehicle (including all drivetrain losses) at all points on a maximum acceleration profile.... to some fixed speed. You could do that by simply integrating the power output as the vehicle goes from zero to, say, the legal speed limit.

Of course, there's an easy way to do exactly that doesn't involve any math. Just take a stopwatch and measure 0-60 performance!

HP is an ok comparable unit, the issue here is that the P85D does not have the advertised hp and owners discovered this because it lacked the power at high speed. I would just like to see the power & torque curve for an EV that actually produces 691 hp and then we can start to go into details of the difference between power & torque curves of different cars.

But all we have at the moment is the power and torque curve of a EV that produces 463 hp ...

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Torque hugely impacts acceleration. C'mon. And what contract are you talking about? Please attach it.

For every car sold there is a contract, at least in Denmark and would imagine as well for the US. The acceleration is specified in a 0-60 mph time and the power of the car in HP on the order page, it does not mention torque, so it would be harder to argued that torque was the reason you bought the car opposed to 0-60 times and HP. You are arguing from a technical point of view.

 

[tomas]

Attach it.

 

[rns-e]

Attach it.

don't need to, you have one of your own

 

[sillydriver]

Torque actually do not matter, as it was acceleration and hp Tesla used to advertise its performance and used to compare the P85D to the other models in the design studio. Torque may matter from a technical point of view but not from a contractual.

I am not going to continue to argue for the positions I have taken earlier in this thread.

I think the quote above fairly characterizes the underlying nature of the dispute, which is cultural. A couple days ago there was a post by someone from Denmark, explaining the consumer protection culture there. In the context of that culture (which is a pretty good culture for the rights of consumers) and the associated laws that back it up, Tesla's position is not good. The focus, as mentioned above, is contractual, where there is an implied contract in all of a company's communications.

It is less straightforward to characterize the opposing culture: perhaps 'holistic' is right, where multiple considerations are brought into the judgment/argument. I'm not going to claim that one culture is better than the other: I personally dislike the notion of cultural relativism, but I think this is one case where it genuinely applies. Nor am I claiming that only Scandinavians are on the contractual side.

But if I am right that this cultural difference underlies the debate in this thread, then we can go on for another 600 posts and nothing will be settled and no one will be brought around to a different position. Essentially we are all just talking past each other. Of course the participants have a right to continue as long as they like, but I will bow out.

 

[Johan]

HP is an ok comparable unit, the issue here is that the P85D does not have the advertised hp and owners discovered this because it lacked the power at high speed. I would just like to see the power & torque curve for an EV that actually produces 691 hp and then we can start to go into details of the difference between power & torque curves of different cars.

But can you just answer one question, with a simple yes/no or correct/incorrect. Is the folllowing statement true or false?

The fact that P85D has motor horsepower rating of 691 is responsible for such a car having roughly 50% higher torque than that of a car with otherwise similar motors, but instead having a combined rating of 463 motor horsepower (i.e. lesser powered motors) with otherwise exactly the same battery and inverter (battery and inverter able to produce a peak power delivery of approximately 345 kW = 463 hp).

 

[tomas]

I replied to a post that said $20k diff from 85D should be compensated due to claimed HP discrepancy. I said that performance of P better so it would not be fair to assert full $20k. Thus I mentioned torque. Rns must not have understood that context. Nonetheless, I'd like to see the exact contract on which he/she is claiming a contractual dispute. I don't have a P85D contract.

 

[sandpiper]

That would be interesting. 10ms of 691hp would make everyone happy then I guess.

Of course it wouldn't. But it WOULD mean that Tesla technically met their advertised output. Unless there is some standard that stipulates how wide the peak power curve has to be? How many ICEs ever achieve their advertised performance?


I'm not claiming that Tesla is clean here. But I also think things are a bit muddier than some folks would have you believe.

 

[Tedkidd]

The Danes have an issue with 0-60 because it doesn't do it in the specified time without a 1 ft rollout. It has nothing to do with horsepower.

In the US, we're used to the 1 ft rollout and the 0-60 times are great as far as I'm concerned. The highway passing power, on the other hand, for a 691 hp 5000 lb car sucks but that's because it's really a sub 500 hp car and not a 691 hp car.

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Had I known the truth I would have never ordered the P85D, so my first choice would be to undo the deal unless they could deliver what was promised.

So for most/many this is an issue of passing performance - acceleration 40 to -say- 100 is much less than expected, and not significantly different than the 85d?

 

[Wilcino]

It's the torque, not hp, that most people love about EVs (not some here obviously). When you punch it at a light and your passenger's head is thrown back against the seat with the EV grin that's where most of the enjoyment comes from. Did people really buy an EV with 1 gear for 80-140mph passing speed?

I haven't bought a Tesla (yet), but that's exactly what I'm interested in. The 1 gear aspect makes no difference, the power output is limited by the battery, if Tesla did a version with an 8-speed DSG it wouldn't perform any faster at high speed. This is also why the power number is important. Without there is no indication of the cars performance at speed. Obviously a 4WD EV car such as a MS is great 0-20, so posts a really good 0-60 compared to an ICE car. Thus it's hard to use this as a reference to high-speed performance. For this peak output power is a better indication (although again is open to interpretation without the entire power curve), which is why the number is useful.

Having only just found this thread, I am surprised by the size of the difference, and it is disappointing. However, I've also had a test drive of the car, so I've had a chance to actually try the passing performance and judge it for myself.

 

[LetsGoFast]

I actually addressed this question before it was posed up-thread - here.

The short answer is that P85D with 463 motor hp will definitely not perform as well as P85D with 691 motor hp (with both variants having max available battery output of 463 hp). In fact such a car will perform *worth* than P85 and 85D.

The fact that this is even a question now demonstrates how much time was wasted on bickering on these threads, with majority of the participants not understanding and not willing to try to understand the core issue at hand. I am saying this because the technical details allowing to answer this question were laid out more than one time.

I find arguing with people about the technical details tiresome and I usually avoid commenting, but I can't ignore this twice. As I understand it, your position is that because the motor is rated for more horsepower that it produces more torque?

Expressed a different way, are you claiming that the motor produces the same torque when drawing 345,398 watts of power at 9,000 rpm as it would when drawing 515,486 watts? If they decided that they have been too conservative on their estimation of the motor's heat tolerance and up the rating to 800 motor hp, will the engine magically begin to produce more torque at 9,000 rpm even as it still only draws 345,398 watts?

If I am given the motor's efficiency at a particular rpm, can I not calculate the torque directly from the input power applied?

 

[SW2Fiddler]

That would be interesting. 10ms of 691hp would make everyone happy then I guess.

Bring it on! I am calling that the "Spruce Goose Demonstration" in my own head. I'd be so entertained for Elon to do that a la Howard Hughes answering his critics by making that plane lift off and FLY ...once.
(Yes, I am aware the official name of the aircraft was the Hercules but everybody knows it by the other nickname!)

 

[vgrinshpun]

But all we have at the moment is the power and torque curve of a EV that produces 463 hp ...

Actually this is inaccurate statement. The P85D has torque curve that is defined by 691 motor hp. The maximum power available from tha battery cuts the top portion of the 691 motor hp curve, imposing 463hp limitation. So the total curve is actually a combination of two curves: "691 motor hp" curve with an over imposed "463hp battery limitation curve". The net result is that 0 to 60 acceleration is mostly defined by the "691 hp motor curve", while high speed performance - by the "463hp battery limitation curve"

For every car sold there is a contract, at least in Denmark and would imagine as well for the US. The acceleration is specified in a 0-60 mph time and the power of the car in HP on the order page, it does not mention torque, so it would be harder to argued that torque was the reason you bought the car opposed to 0-60 times and HP. You are arguing from a technical point of view.

For every car sold in Europe there is also a Certificate of Conformity which lists motor power ratings per ECE R85 which are measured without considering limitations imposed by the vehicle propulsion battery. It is one of these ratings that Tesla used on their ordering page. I find it inconceivable that Danish authorities can find Tesla at fault for using power ratings that are shown on the Certificate of Conformity of the car.

As far as torque goes, it is not relevant whether it was listed anywhere or not. The fact of the matter is that 0 to 60 time advertised by Tesla is consistent with the advertised 691 motor hp. This acceleration is **not** consistent with the horsepower that corresponds to the limitation imposed by the battery (463hp).

 

[LetsGoFast]

But can you just answer one question, with a simple yes/no or correct/incorrect. Is the folllowing statement true or false?

The fact that P85D has motor horsepower rating of 691 is responsible for such a car having roughly 50% higher torque than that of a car with otherwise similar motors, but instead having a combined rating of 463 motor horsepower (i.e. lesser powered motors) with otherwise exactly the same battery and inverter (battery and inverter able to produce a peak power delivery of approximately 345 kW = 463 hp).

Input power, output power and torque are all intrinsically linked mathematically. At 345 kW of output power (hp at shaft), you are producing a defined amount of torque that is governed by the following formula:

Pout = τ * ω

345kw = torque * speed. I'd suggest that you read this site.

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The fact of the matter is that 0 to 60 time advertised by Tesla is consistent with the advertised 691 motor hp. This acceleration is **not** consistent with the horsepower that corresponds to the limitation imposed by the battery (463hp).

What? The horsepower that is output at the shaft, which is limited by the battery, wires, fuses, etc is the mathematical definition of the power output by the motor. It is a Newtonian measure of work generated. Is there some other magical source of power that is pushing the car forward? There is only one source of propulsion in this car. It is beyond axiomatic that the amount of horsepower it ouputs is sufficient to account for the performance characteristics of the car. I'm not sure I can read this thread any more today without stabbing a sharp object in my eye.

 

[Wilcino]

I find arguing with people about the technical details tiresome and I usually avoid commenting, but I can't ignore this twice. As I understand it, your position is that because the motor is rated for more horsepower that it produces more torque?

Expressed a different way, are you claiming that the motor produces the same torque when drawing 345,398 watts of power at 9,000 rpm as it would when drawing 515,486 watts? If they decided that they have been too conservative on their estimation of the motor's heat tolerance and up the rating to 800 motor hp, will the engine magically begin to produce more torque at 9,000 rpm even as it still only draws 345,398 watts?

If I am given the motor's efficiency at a particular rpm, can I not calculate the torque directly from the input power applied?

Yes to the first paragraph, no to the second.

The motor is coupled with power electronics that limit the amount of (electrical) power that can be drawn by the motor. A motor has a power limit beyond which it will become damaged. This is in some way related to the rpm of the motor, thus producing a limit curve, which the electronics follow. Building a motor that can accept more power (adding windings) without damage will, in general, move the curve up but not change the curve substantially. A motor that is rated for more power will have its electronics changed to increase the limit it can draw. Thus a motor that is rated for more horsepower will produce more torque at all speeds, as long as supplied with enough power from the source.

If Tesla decide they have been conservative of the motors rated horsepower they will modify the power electronics to allow it to draw more power from the source, increasing its rating. Thus the motor will produce more torque at 9,000rpm as long as the source can provide it.

As to paragraph 3, yes you can, although efficiency is also based somewhat on the input power level as well as RPM.

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But can you just answer one question, with a simple yes/no or correct/incorrect. Is the folllowing statement true or false?

The fact that P85D has motor horsepower rating of 691 is responsible for such a car having roughly 50% higher torque than that of a car with otherwise similar motors, but instead having a combined rating of 463 motor horsepower (i.e. lesser powered motors) with otherwise exactly the same battery and inverter (battery and inverter able to produce a peak power delivery of approximately 345 kW = 463 hp).

Yes at some (lower) speeds. No at other (higher) speeds. I cannot condense that further to a yes or no, it requires knowledge of the rpm.

 

[bonnie]

Well now we have an internet troll reading this thread & cherry picking comments to suit his reality. Never mind that it was hypothetical.

Reading comprehension doesn't appear to be his strong suit.