What if Tesla would give P85D owners free ludicrous update?

[NigelM]

I'm seriously puzzled to why people don't have a problem being lied too, especially over something that involves over 100k.

The oil industry has been lying to us for years and that involves billions of dollars.

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Tesla doesn't rate HP consistently across its AWD models, which makes you wonder.

I get the point about consistentcy but I have to say I've been talking about my Teslas (Roadster & Model S) for 4 1/2 years now and I don't ever recall mentioning, nor anyone asking about, horsepower. The cars are incredibly fast already and there's rarely an occasion to truly push it to the limit anyway. Maybe I'm an outlier.

 

[Saghost]

Three independent dyno tests have not had any problems and results are between 413 and 460 hp

US dyno by Brooks 413: http://www.dragtimes.com/2015-Tesla-Model-S-Dyno-Results-Graphs-27143.html

DK dyno 430: http://teslaforum.dk/ow_userfiles/plugins/base/981-Tesla_Dyno.png

FIN dyno 460:http://www.teslaclub.fi/blog/22/P85D+dyno-testissä/

None of these dyno plots follow the actual observed acceleration curve of the vehicle, and all of them claim impossibly low torque values, which at least one repeatedly says is at the wheels. 864 Ft-lbs on a 1.16 foot radius (245/35R21 nominal) would be 747 pounds of acceleration force - which on a 4800 pound car is .16g.

Consumer reports clearly demonstrated a nearly constant 1g+ acceleration for nearly 2 seconds:

That requires somewhere in excess of 5500 ft-pounds at the wheels for a 4800 pound car on 245/35R21s - seven times the highest number reported on any of those dyno runs. Combined with the different curve shape, it makes me uncertain of the test results...
Walter

 

[bonnie]

I get the point about consistently but I have to say I've been talking about my Teslas (Roadster & Model S) for 4 1/2 years now and I don't ever recall mentioning, nor by one asking about, horsepower. The cars are incredibly fast already and there's rarely an occasion to truly push it to the limit anyway. Maybe I'm an outlier.

I've shown my Roadster at countless events & I've always been asked about foot torque, not horsepower. My experience, but 4+ years worth & thousands of interactions at events.

 

[AmpedRealtor]

I get the point about consistently but I have to say I've been talking about my Teslas (Roadster & Model S) for 4 1/2 years now and I don't ever recall mentioning, nor by one asking about, horsepower. The cars are incredibly fast already and there's rarely an occasion to truly push it to the limit anyway. Maybe I'm an outlier.

I agree with this, although to be fair, most of the people I talk to about the car are not performance enthusiasts. I've sold two to acquaintances and none of them asked me about the horsepower rating. But I can appreciate that there are those for whom it is important.

 

[darthy001]

The oil industry has been lying to us for years and that involves billions of dollars.

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I get the point about consistently but I have to say I've been talking about my Teslas (Roadster & Model S) for 4 1/2 years now and I don't ever recall mentioning, nor anyone asking about, horsepower. The cars are incredibly fast already and there's rarely an occasion to truly push it to the limit anyway. Maybe I'm an outlier.

I've shown my Roadster at countless events & I've always been asked about foot torque, not horsepower. My experience, but 4+ years worth & thousands of interactions at events.

I agree with this, although to be fair, most of the people I talk to about the car are not performance enthusiasts. I've sold two to acquaintances and none of them asked me about the horsepower rating. But I can appreciate that there are those for whom it is important.

Most norwegians have been carpetbombed by the media in norway about the Tesla with 700hp so that comes up alot here... Not that I see why that is relevant in this thread....

 

[sorka]

None of these dyno plots follow the actual observed acceleration curve of the vehicle, and all of them claim impossibly low torque values, which at least one repeatedly says is at the wheels. 864 Ft-lbs on a 1.16 foot radius (245/35R21 nominal) would be 747 pounds of acceleration force - which on a 4800 pound car is .16g.

Consumer reports clearly demonstrated a nearly constant 1g+ acceleration for nearly 2 seconds:
That requires somewhere in excess of 5500 ft-pounds at the wheels for a 4800 pound car on 245/35R21s - seven times the highest number reported on any of those dyno runs. Combined with the different curve shape, it makes me uncertain of the test results...
Walter

That depends on how the operator calculates torque. If they do it at the wheels, then you will see proportionally higher values than if you use the gear ratio and back calculate it to the motor shaft. This is why you see P85's that produce 430 rwhp with torque in the in the 440s or 4300 depending on whether you use the 9.73:1 final drive ratio.

 

[Uncle Paul]

Comparing Electric HP to internal combustion HP is always going to be difficult to compare.

Gas engines usually produce their maximum HP near their maximum RPM limit. At Zero RPM the produce Zero HP.

Electric motors produce maximum HP at zero RPM and taper off as their RPMs rise.

Maximum torque is a different matter. Gas engine produce Zero torque at Zero RPM, and maximum torque somewhere between Zero RPM and redline.

The advantage of an electric motor is the near Zero lag between accelerator actuation and torque being delivered to the road surface. In a internal combusion engine, speed increase needs many things to happen before maximum thrust. The throttle pedal sends an electric signal to the throttle to open fully, another signal is delivered to the transmission to down shift into a higher reving gear. Another signal is sent to the throttle to reduce available torque as to not damage the transmission of drive line. Then when everything is sorted out it begins to optimize the torque to the road surface. If traction is sensed to be insufficient, the electronic traction control system will reduce power until the tires are fully hooked up. Then additional throttle may be applied until slip is again detected.

Because of all these variable, it is difficult to perfectly determine output.

In Tesla's case I believe writers just took the HP ratings of the two electric motors, added them together, and published the 691 ratings. This most likely was done prior to instrumented testing, and perhaps just an honest mistake, being caught up in all the dual motor hype.

Tesla is brand new to this dual motor thing, and believe everyone was wrong about publishing the ratings, but can easily see why it happened.

I have a girlfriend, whom I love dearly, but one of the things that irritate me the most about her is when she throws "BUT YOU SAID!!" in my face. Maybe this is why I feel that way about this...BUT YOU PROMISED! argument.

 

[stopcrazypp]

In Tesla's case I believe writers just took the HP ratings of the two electric motors, added them together, and published the 691 ratings. This most likely was done prior to instrumented testing, and perhaps just an honest mistake, being caught up in all the dual motor hype.

That exactly what I see happened. That's why they pulled the combined motor power number. They actually did the same mistake with the 85D and 70D, but nobody noticed there.

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Riddle me this... why does Tesla advertise the 70D and 85D with actual HP (no statement about "motor power"), but the P85D with "motor power"? Take a look at the order page right now - "motor power" does not appear anywhere in the 70D and 85D specs, just a stated HP figure. When you look at the P85D, suddenly the term "motor power" appears. Not only that, but the P85D's motor power figures have now been increased to a combined 762 HP (259 HP front, 503 HP rear) if you are inclined to add them up. And that's WITHOUT the Ludicrous upgrade.

Tesla doesn't rate HP consistently across its AWD models, which makes you wonder.

Unless you are looking at a different page than me, 70D and 85D also has motor power ratings:
70D: 328 hp / 259 hp front and rear motor power
85D: 417 hp / 259 hp front and rear motor power

http://www.teslamotors.com/models#battery-options

This was true ever since the launch of the P85D:
http://www.teslamotorsclub.com/show...eement/page4?p=1076026&viewfull=1#post1076026

The major difference is Tesla never published a system power number for the P85D. I suspect the reason is that the P85D crowd was the only one that took issue with Tesla over the "motor power" thing (starting with the "691hp" thread, which Tesla did respond to by removing the number), and publishing such a number will only make things worse in this regard. Tesla is in a lose-lose situation right now and I think the Ludicrous mode discount is their effort to turn that around.

 

[sorka]

Electric motors produce maximum HP at zero RPM and taper off as their RPMs rise.

You confused hp and torque. It's the torque that starts out high decreases as RPMs increase when kw input is constant. KW in will == HP out if the motor were 100% efficient at any RPM. They're not 100% efficent, but they're pretty close in a very wide RPM range so the HP curve with a constant KW input will look very flat. Torque will start off in the upper left and head down to the lower right as RPMs increase.

Please don't confuse this with graphs that show flat torque and increasing hp over the RPM range as those examples are increasing KW input linearly.

My REST KW logged values match exactly the the vbox produced rwhp minus about 9% across the board. The only reason you don't see linear torque values on the dynos or vbox graphs is because power from the battery builds up from 0 to 415 KW at 36 MPH. If they just dumped the full 415KW in all at once, your torque would be so high that you'd just spin all 4 wheels at even a fraction of that.

Electric motors produce maximum torque at 0 RPMs. Don't confuse it hp.

 

[NigelM]

I have a girlfriend, whom I love dearly, but one of the things that irritate me the most about her is when she throws "BUT YOU SAID!!" in my face. Maybe this is why I feel that way about this...BUT YOU PROMISED! argument.

Hopefully that had nothing to do with the size of your horsepower?

 

[Saghost]

That depends on how the operator calculates torque. If they do it at the wheels, then you will see proportionally higher values than if you use the gear ratio and back calculate it to the motor shaft. This is why you see P85's that produce 430 rwhp with torque in the in the 440s or 4300 depending on whether you use the 9.73:1 final drive ratio.

Agree with what you said. However, the article associated with the first link repeatedly said "at the wheels," and never mentioned any gear ratios:

Tesla Model S P85D Shocks the Dyno with 864 ft-lbs of Torque | DragTimes.com Drag Racing, Fast Cars, Muscle Cars Blog

I don't speak the languages the other two links are in, but nothing I saw in them with Google Translate indicated what ratio if any they were using to calculate torque.

As far as I know, the two motors are geared differently, so unless you measure and report them independently, "at the wheels" is the only way that is correct - the Mustang AWD dyno from the first link mechanically connects the rollers to keep the speed constant, and thus only outputs one number; not sure how the others were done.
Walter

 

[lolachampcar]

This whole idea of torque, dynos and electric cars is a bit of a misnomer in that "torque" is traditionally that generated at the crankshaft of an engine or motor. Horsepower spins the dyno's drum (for inertia dynos which are most popular in the US) and an engine RPM probe is used to back calculate crankshaft torque to achieve the particular drum acceleration. Given that there is no way for the dyno to know a Model S' motor rpm, there is no way for it to calculate engine shaft torque.

Now anything that spins up the dyno's drum is exerting a torque on that drum. The dyno can easily determine this torque but I'm not aware of anyone using "torque applied to the drum" as a measure of comparison as this would be dyno specific. Anyone know of people using torque to drum as a measure for comparison?

 

[sorka]

Normally dynos are done in the 1:1 gear ratio. For instance, if you dyno a 300ZX twin turbo in 4th gear, the ratio is 1:1 so the torque at the shaft is the same as the torque at the wheels. The Tesla obviously can't do that because it's stuck at it's final drive ratio. Making it even more complicated, the rear is 9.73 and the front is 9.34 so if you're going to calculate torque at the shafts, the best you can do is split the difference:

Here's a vbox run with torque calculated at the shafts:

Here it is again but at the wheels. In this case, we don't have to be confused by different final drive ratios between the front and rear motors:

Notice how torque is a function of g's.

As far as I know, the two motors are geared differently, so unless you measure and report them independently, "at the wheels" is the only way that is correct - the Mustang AWD dyno from the first link mechanically connects the rollers to keep the speed constant, and thus only outputs one number; not sure how the others were done.
Walter

The Mustang dyno indeed only has one PAU and physically links both front and rear drums together with a toothed belt. The Dynojet has independent rollers with two PAU's but you can't normally test AWD cars in that configuration because the transfer case could allow the front and rear axles to spin at different speeds. So why does the Dynojet have this setup? Because you can't test 4WD cars on a dyno that has a linked drums without slippage for the same reason you can't drive a 4wd vehicle on solid slip free ground. You can only drive a 4wd vehicle in snow, mud, sand, gravel, etc. So if you want to dyno a 4wd car you need to use a Dynojet. If you want to dyno an AWD car on a Dynojet, then you need to use the Linx system which is belt that ties the front and rear drums together. In this configuration, each PAU no longer tests each drum independently.

If the Mustang dyno operator is trying to get torque at the shafts, they really better know what they're doing when calculating final drive ratios when they are aren't the same. In this case, because they are very close, it doesn't make that much difference on torque even if they use only the front or back. Or they can just use the wheels which I agree is the right thing to do in this case.

Regardless of how you calculate torque, the hp calculation is unchanged.

 

[lolachampcar]

Some cars have a gearbox ratio that is 1:1 but then there is the final drive ratio. I guess if some dynos are requiring an existing overall ratio input they could easily calculate engine/motor output shaft torque and engine/motor rpm.

 

[Saghost]

Notice how torque is a function of g's.

Well, no. It's certainly a valid point that they are related and always proportional, but it's really the g's that are a function of torque (and weight of vehicle and tire diameter) - the g is the result of the torque applied, not the other way around.

 

[lolachampcar]

details

 

[sorka]

Well, no. It's certainly a valid point that they are related and always proportional, but it's really the g's that are a function of torque (and weight of vehicle and tire diameter) - the g is the result of the torque applied, not the other way around.

Yes. I miss wrote:smile:

The reason I pointed that out is because when folks post that CR graph of the P85D with the Hellcat they'll know that when g force rises or falls that torque follows it which is missing from the graph.

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Some cars have a gearbox ratio that is 1:1 but then there is the final drive ratio. I guess if some dynos are requiring an existing overall ratio input they could easily calculate engine/motor output shaft torque and engine/motor rpm.

Yup, and if you don't know that is and don't convert it right, then you won't get torque at the engine in the absence of an RPM signal.

The vast majority of dyno operators use the induction probe on an ignition coil or test loop(in the case when the transformers sit directly on the spark plugs) to read the engine RPM directly. Using gear ratios back from the wheel RPM is a fallback technique when it's difficult to get an RPM reading which is far more common these days to have that issue.

 

[stopcrazypp]

I thought the "eddy current" dynos like the Mustang dynos measure torque and calculate power from that, while the Dynojet measures power and calculates torque? They don't work the same way.

 

[sorka]

I thought the "eddy current" dynos like the Mustang dynos measure torque and calculate power from that, while the Dynojet measures power and calculates torque? They don't work the same way.

That's often a point of confusion. The mustang dyno has an electric motor that is used as the PAU to apply a counter force. It measures the torque applied against it regardless of the vehicles wheel RPM or motor RPM. It then calculates hp from the torque using either the drums RPM or PAU RPM(it doesn't really matter).

Then to calculate torque of the vehicle for either the wheels, need the hp and either the wheel RPM or the final drive ratio back to the motor shaft or you need a probe on the ignition to record motor RPM directly.

I have a mustang dyno run from my 300zx twin turbo where the dyno operator refused to input the final drive ratio and he couldn't get a probe reading off the ignition, so the dyno shows only hp and not torque.

 

[skilly]

@Matias - One thing we know for sure at this point is that the fan boys and girls wouldn't care if it said 691 HP on the window sticker, the website, or if a tattoo on the CEO's face also confirms it. They'll still find some way to spin it so that we're wrong for pointing out that Tesla screwed us over on horsepower when multiple tests show it's incapable of reaching the advertised value. lol.

I have a P85D....Finally, a sobering thought in this thread.

TM is full of half truths and misinformation...they don't handle their own messaging well at all - and they are the masters of it. With this car, it was my first experience dealing with them. They misquoted range and then silently adjusted the spec after people had ordered (without telling them). They spoke of the HP totals and had no testing data to back it up...there was supply chain challenges to the tune of people canceling their orders....and this "ludicrous" mode...that was previously a brag by Elon releasing to the market that he could push the car into the sub 3 second 0-60 realm....I agree there was no mention on whether it was going to cost users; however, lets be real with the information as it was shared.it was implied that it would be done through the typical pushed S/W upgrade.

This site is just an abundance of valuable information, but sometimes its very frustrating to read some of the defending comments around a company that should really be doing better at communicating its offerings to the public. Im not asking for anything that I don't see as unreasonable for what is a 6 figure depreciating asset. This company isn't a start up anymore and we shouldn't be giving it such a wide berth for very poor corporate communications.