[updated with *] P85D 691HP should have an asterisk * next to it.. "Up to 691HP"

[p85dk]

Definitely interested in the outcome of this. Please keep us updated.

So the car was at Tesla for testing last week. I have not heard anything from them yet - but this is the numbers from the REST API from their testing:

From these data it did not look like they were able to hit the magic 3.3s for 0-100 km/h - actually, having only one out of ten tests only coming close to 3.4s is not good enough. However I thought it was strange to see that the kW input was once again at 415kW. So i went out and did a little bit of testing my self. I did the test in the early evening at 20 Celsius, A/C and radio off and only me in the car. Original Tesla 21" with 265 in the back. And these were the numbers:

So I got one as close to the 3.3s as nearly possible - but the funny thing is that it still does not feel as fast as it did when I got the car back in April. It's close but not really the same. Unfortunaly I do not have the REST API data from back then with the .124 sw.

Ohh - and as you can see, when the battery gets warm, the times drops fast

 

[jerjozwik]

so... has anyone logged the output of the 85D to this level? wonder if its getting 4.4, more or less?

3.1 is worth the extra 25k. 3.8... i dono.

 

[Stoneymonster]

So the car was at Tesla for testing last week. I have not heard anything from them yet - but this is the numbers from the REST API from their testing:

Does the REST API have sufficient resolution to determine 0-60 time with that level of precision? I highly doubt it.

 

[wk057]

Does the REST API have sufficient resolution to determine 0-60 time with that level of precision? I highly doubt it.

The answer is no. The streaming API is unpredictable and doesn't match my PBox runs.

 

[stopcrazypp]

However I thought it was strange to see that the kW input was once again at 415kW. So i went out and did a little bit of testing my self. I did the test in the early evening at 20 Celsius, A/C and radio off and only me in the car.

So your car outputs 415kW (~550hp), but your dyno was only 320kW/430hp (the same as a P85 that outputs 350kW according to REST). I have a hard time believe there is a drive-line loss of 120hp (22%) while a P85 has only a loss of ~8% in comparison. While I remember you said something about losses being double because of two motors, I don't believe that is how the math works. The loss as a percentage should be the same.

For example, say the front motor loses 10% and has X hp. Rear motor loses 10% and has Y hp. Total power with no losses would be X+Y hp. The overall loss would be (by distributive property):
(0.1X + 0.1Y)/(X+Y) = 0.1 (X+Y)/(X+Y) = 10% overall. You do not add the two 10% and get 20% overall.

 

[p85dk]

So your car outputs 415kW (~550hp), but your dyno was only 320kW/430hp (the same as a P85 that outputs 350kW according to REST). I have a hard time believe there is a drive-line loss of 120hp (22%) while a P85 has only a loss of ~8% in comparison. While I remember you said something about losses being double because of two motors, I don't believe that is how the math works. The loss as a percentage should be the same.

For example, say the front motor loses 10% and has X hp. Rear motor loses 10% and has Y hp. Total power with no losses would be X+Y hp. The overall loss would be (by distributive property):
(0.1X + 0.1Y)/(X+Y) = 0.1 (X+Y)/(X+Y) = 10% overall. You do not add the two 10% and get 20% overall.

well, i don't know. I only have the two numbers - the energy drawn from the battery and the energy output at the wheels. HOWEVER, the 415 kW is at a 100% battery level, and the dyno was done at 70% battery, since we could not get the charger to work. But lets just say that the loss is 8%, so we do not talk about a number none of us know what is, then is would be 415kW minus 8% = 381kW/511hp which is still somewhat lower than the advertised 691hp.

I have a previous run at approx 70% where it shows that it draws 370kW from the battery so if we take the dyno reading of 320kW the drive-line loss would be approx. 13%, which would make it approx. 480hp.

I think the best thing is to get as much data into the thread as possible - my only agenda is to figure out if what I bought is actually what I was sold.

- - - Updated - - -

The answer is no. The streaming API is unpredictable and doesn't match my PBox runs.

I suspect the same, but I do not have a PBox. Could you maybe show us some comparative data from the PBox and REST API from the same runs to give us an idea about how accurate the REST API is?

 

[thegruf]

my only agenda is to figure out if what I bought is actually what I was sold.

You achieved 3.3 secs so the answer to this question is unequivocably yes.
No data has been provided by Tesla to address performance vs SoC afaik, so it is not reasonable to challenge this.

you achieved @415KW which is a long way short of the 515KW motor power.
This will affect performance at higher speeds much more so than the 0-60 sprint.
The question is therefore do you believe you were sold a 691hp(515KW) car or a car with 691hp(515KW) motor power but limited to 415KW by other power source components.

This last point is where I do believe Tesla have tripped up with the accuracy of their sales material, hence the tweaks to the website information to clarify.

Of course they do also have a problem with power figures explaining how an P85D is 25% faster 0-60 than an 85D, (when both appear to consume similar peak KW)
Really this is only explained by a graph showing the much steeper gradient of power application vs time in the P85D.

Lastly of course is the question of whether the 85D is artificially constrained?

 

[p85dk]

You achieved 3.3 secs so the answer to this question is unequivocably yes.
No data has been provided by Tesla to address performance vs SoC afaik, so it is not reasonable to challenge this.

The answer is no. The streaming API is unpredictable and doesn't match my PBox runs.

I understand wk057s post as questioning the validity of the REST API data, hence the 3.3 sec - but with that in mind I still think we are getting close and I believe that it will be able to do it in the right conditions, which would make me a happy owner. But I would like to have it available at a broader range of SoC

you achieved @415KW which is a long way short of the 515KW motor power.

A very long way as the 415kW is energy into the motor and not actual motor power

This will affect performance at higher speeds much more so than the 0-60 sprint.
The question is therefore do you believe you were sold a 691hp(515KW) car or a car with 691hp(515KW) motor power but limited to 415KW by other power source components.

Yes it will affect higher speeds and I believe I was sold a 691hp car and not a limited car. If it is limited they are still not telling people that. The only limitation they talk about is top speed limited to 155mph, not a word about limited motor power.

This last point is where I do believe Tesla have tripped up with the accuracy of their sales material, hence the tweaks to the website information to clarify.

I still don't think they have clarified anything as they still do not tell us what that actual hp is for the P85D as they do with all the other models.

Of course they do also have a problem with power figures explaining how an P85D is 25% faster 0-60 than an 85D, (when both appear to consume similar peak KW)
Really this is only explained by a graph showing the much steeper gradient of power application vs time in the P85D.

Lastly of course is the question of whether the 85D is artificially constrained?

I think the difference is down to the bigger motor at the back being able to produce more torque - but I don't know for sure

 

[wk057]

I suspect the same, but I do not have a PBox. Could you maybe show us some comparative data from the PBox and REST API from the same runs to give us an idea about how accurate the REST API is?

I will as soon as I get some time to either look through my existing data and/or compile some new data. Time is a little limited for the near future, unfortunately.

Basically it seems that the timestamp on the streaming API isn't quite right. The data in each line seems correct, but it doesn't necessarily correspond exactly to the timestamp given. If I had to guess I would say the data is timestamped at Tesla's servers without taking into account data transmission latency, but that's just a theory.

 

[3mp_kwh]

Don't most of the magazines represent "0-60" times with a one foot roll-out, to control for reaction time? I think that is pretty common, where false HP claims aren't.

I wish there were an 81 page thread to turn 'TC off'...

 

[Cary p85d]

I have had mine since December. I just went on an 8000 mile road trip and I have not noticed this.

 

[brianman]

I have had mine since December. I just went on an 8000 mile road trip and I have not noticed this.

Welcome to the forum. Can you clarify the "this" in your post? Thanks.

 

[Alipapa]

One can debate the 0-60 times can be vary depends on roll-out. However, the fact we all know and is that the battery isn't giving enough power to the motors to support the previously advertised 691HP. Please keep us updated, and I appreciate all the work you have done. (My P85D just entered production)

 

[WarpedOne]

Of course they do also have a problem with power figures explaining how an P85D is 25% faster 0-60 than an 85D, (when both appear to consume similar peak KW)

They do not have any such problem.

P85 reaches peak kW at 42mph and 'holds' it up to 72mph. Under 42mph P85 is "max-torque" limited, this is actually 'max current through inverter/motor" limitation. Under 42 mph two motors can output higher total torque and hence achieve stronger acceleration because battery can supply more than a single motor can transform into rotation.

Between 42 and 72mph there is battery power limitation in P85 and not much can be helped by two motors.
Above 72mph total output power of P85 is again below peak kW and two motors can again output more than a single one.

So, in P85D this maximum battery power is available in wider speed window than in P85.

How much wider? Not enough data was published to calculate exact numbers.
IF P85D had same motor in front and rear as P85 has in the rear, than max battery power could be output from 21mph up to about 150mph.
But P85D has a weaker motor in front, about half as strong as the rear one so I would guess P85D reaches maximum power around 33mph and can "hold" it up to around 100mph.

Does this explain faster 0-60 times and livelier response at high speeds? Yes it does, totally.

Edit: I've misread 85D as P85.

Still, the basis of explanation holds - power output of electric motor is directly dependent on its RPM. From 0 to some X rpm it can output maximum torque. Power at X/2 RPM is therefore only half the power at X RPM.
A motor with higher starting torque will have higher power than a motor with lower torque until some outside power limitation is reached. Like a maximum power that can be drawn out of a battery.

 

[thegruf]

@Warpedone - oh I get the discussion absolutely.
But if you paint it simply as an hp figure and torque figure you would find the figures not very different and then find you cannot sell the higher performance model so easily.
See Tesla website ... why do you think the P85D is rated as it is?

In reality graphs are needed, not just max figures, though manufacturers often withold these as the detail can be too revealing.

In my case I chose the 85D based on the nature of my driving
I do very few "launches"
My typical commute means I hoof it out of roundabouts very regularly so 30mph+ acceleration is important
I have no intention of losing my driving licence, so speeds above a reasonable interpretation of the speed limit are unimportant to me
I will not be tracking it (will have to get something lighter & more agile for that)
I understand the 211hp motor is of a later design than the 470hp motor with "many lessons learnt", so (without proof) I hope for slightly better thermal performance and efficiency overalll.
afaik there are no other differences eg suspension between the models. There is a possibility that the P85D might feel more rear biased (which would be preferable) than the 85D with the larger motor at the rear delivering more shove but I have seen no comment about this here, so assume it is unnoticeable.

Due to the above, the $20K doesnt stack up for me, and I believe I will find in my typical speed range that there is little to difference between 85D and P85D.
Had the P85D genuinely been able to use the full 691hp I would expect the 30-70 times to be shatteringly fast, not just 525hp ish very rapid we are witnessing, and that would certainly have altered my purchasing decision

That said $20K could be viewed as an absolute bargain for 4.2->3.1 seconds 0-60 for many people for whom this particular aspect of performance is relevant to their driving.

... and if Tesla do release a battery capable of sustaining a larger current drain (the most likely limitation), then P85D owner are going to be very happy indeed, if a little poorer

 

[Gimlet]

If you look at the simple hp figures for the motors of the 85D then the total output added together in the same way as they are adding together the motor outputs of the two P85D motors would be 2 x 257 hp = 514 hp yet they choose to quote the power at 422 hp.

 

[WarpedOne]

But if you paint it simply as an hp figure and torque figure you would find the figures not very different and then find you cannot sell the higher performance model so easily.

I'm sure quite some cars were sold on the basis of misunderstanding the 691 HP figure.

In reality graphs are needed, not just max figures, though manufacturers often withold these as the detail can be too revealing.

+1

Those graphs can be plotted with a good dynorun. Still there are none to be seen

 

[Espen W]

Which begs the question, then, when Musk said that at 3.2 seconds the P85D would be as fast as the McLaren F1, was that a fair and accurate statement, and both cars were being timed using 1-foot rollout, or was the McLaren F1's time a true 0-60, 3.2 second time, while the P85D's time included the 1-foot rollout, in which case the P85D was not as quick as the F1.

I tried to dig into this a while back, and posted about it, and while I couldn't come up with anything conclusive, the evidence seemed to point to the McLaren's time also including rollout. I'd certainly like to know, though, if anyone has any definitive answer on this.

I'll look for the post I'm talking about, and edit this post to include the link to it.

Edit: Here's the link, and the post: P85D vs GTR - PerformanceBox data vs drag strip slip data... help? - Page 3




Edit Number 2: Dennis--You wrote:

The above, though not conclusive by any means, would seem to indicate that Autocar --DOES-- use rollout when testing. Can you provide some evidence that they do not? If so, that would mean the comparison of the P85D to the McLaren F1 was not a fair comparison.

The journalist that wrote the above text for Autocar back in the day didn't mention rollout because he likely did not even know what it was. While drag strip testing and terminology is second nature to American auto journalists, it is Greek to most Europeans, as drag strips are few and far between.
Using rollout for time to speed measurements would be regarded as ridiculous in Europe, where some magazines don't even use rollout for 1/4 mile time to distance runs (note that some do 0-400m instead of 0-1/4 mile (402m). Other than rollout, the US test protocols make more sense, as they test with driver only (Euro tests are usually done with passenger) and the US tests are run with a limited amount of fuel. The Germans test with a full tank, and that is a drawback for cars equipped with a bigger gas tank.
Autocar tested the McLaren F1 0-30mph in 1.7s, and they famously tested the Porsche built Audi RS2 (I own one) to a F1 beating 1.5s (on the way to a 4.8s 0-60, which was nuts quick for a station wagon back in 1994. It requires side stepping the clutch at 7000rpm, though, so I have never tested it for fear of breaking something in the drivetrain, especially with close to twice the stock power/torque on board. Almost no stoplight type intersections left in this country (Norway), so I focus my tuning efforts on swiftness in the 50-70mph and 60-90mph ranges.

 

[jerjozwik]

well get to it guys! there are more than enough p85Ds out in the world by now! call up your friends and do some runs... for science!

[still gona order a p85d, regardless]

 

[thegruf]

and the reason no "good" runs have been done is that the Tesla is not geared. So the torque rips the Dyno's apart.
The best you can hope for is some runs with a rolling start to mitigate the torque peak at low rpm.