P85D and P90D horsepower disagreement

[brianman]

However, that actually isn't really required. We know the "470hp" claim for the rear motor is plausible given 430whp measured for the P85. We don't have independent tests of the front motor being "221hp", but the S85D has the power meter go to ~320kW (429hp), which splits out to 215hp. So both motor ratings are plausible.

Of course, you can say the wording was misleading (and I think Tesla agreed, which was why they removed it), but again my argument is over what they really meant with that wording.

Engineering question.

Is gearing also a potential reason for the "addition problem"? More specifically, electrical aspect aside, might the gearing be such that you can't mechanically have both motors "full out" with mismatched HP and gearing they have between the front and rear motors?

Your note about the other *D flavors reminded me that all the other flavors have matched front and rear motors such that (my simplistic view of the world) imagines they can easily run half-half, full-0, and 0-full power application in the symmetric motor vehicles for "full acceleration", "torque sleep FWD", and "torque sleep RWD". With different motors (and gearing) it's a harder problem - no?

 

[stopcrazypp]

Engineering question.

Is gearing also a potential reason for the "addition problem"? More specifically, electrical aspect aside, might the gearing be such that you can't mechanically have both motors "full out" with mismatched HP and gearing they have between the front and rear motors?

Your note about the other *D flavors reminded me that all the other flavors have matched front and rear motors such that (my simplistic view of the world) imagines they can easily run half-half, full-0, and 0-full power application in the symmetric motor vehicles for "full acceleration", "torque sleep FWD", and "torque sleep RWD". With different motors (and gearing) it's a harder problem - no?

Interesting question. I think that is a possible issue. If the peak power point of the two motors do not match it is possible that it is never able to deliver 691 hp together. It is the same reason why hybrids don't just add the peak power numbers of the ICE and motor to get their power rating.

This is somewhat alleviated however by the fact that the peak power region of an electric motor is not a point at the very end of the graph (like an ICE), but rather closer to a plateau near the middle (so having an overlap is much easier).

It is probably possible to graph this given we know the final drive is 9.34 (front), 9.73 (rear). I will have to dig up some power graphs of the two motor versions.

It would be nice if there was a dyno able to map the power output of the front and rear independently. Of course we can still verify total power with a P85D L or P90D L dyno (assuming we can solve the issues that dynos seem to be having measuring the power of the dual motors).

 

[brianman]

If the peak power point of the two motors do not match it is possible that it is never able to deliver 691 hp together.

Unless they've done "significant retuning" of the rear motor vs. the original P85, I would expect the P85D's rear motor to be essentially unchanged. If that assumption is correct, then the rear motor would have its "peak power region" at the low end (0-30).

When they described torque sleep in the blog post, I recall that the benefit in the P85D is "optimal" if the rear is slept because the front is more efficient. If that's the case, then I would expect that the front motor would have its "peak power region" more on the higher end (30-60 or 40-70).

If both theorycraft conclusions are correct, perhaps the "peak power regions" don't overlap at all (0-30 with 30-60, or 0-30 with 40-70).

How does this help? Well...

1. An aftermarket track tuner could adjust/replace the front motor such that the "peak power region" of the rear is more like the front. This could improve the 40-60 passing acceleration significantly, and perhaps enable a higher top speed and improved highway range.
2. An aftermarket drag tuner could adjust/replace the rear motor such that the "peak power region" of the front is more like the rear. This could improve the 0-60 acceleration significantly, but perhaps at the expense of top speed and highway range.
3. An aftermarket range tuner could adjust/replace both motors such that the "peak power region" is in the 60-90mph range, which might make it accelerate "poorly" (S40 anyone?) but give you very extensive highway range.

Or maybe I'm not really understanding this all and dreaming.

 

[sorka]

I never claimed the car did make 691hp (in regards to the car today right now as it is with no modifications or updates). I only claimed you were misinterpreting what they mean with the "motor power" rating. My point was that the wording they used only promised the motors are capable of 691hp. If the "ludicrous" update enables 691hp at the wheels or crank with no change to the motors, then that proves they were not lying about their claim.

All it proves is that the motors will turn into kenetic energy whatever power is shoved into them. Electric motors do that. They'll keep on putting out more and more whatever you shove into them until you reach some limit and they blow up or burnout.

Now they have different higher numbers for each motor with the L update. No auto manufacturer that produces ICE vehicles can claim some motor power that their motor could produce if you upped the boost, increased the air fuel mixture, opened up the exhaust, or intake. They have to specify what it actually makes as equipped. The mid 90's supra was famous for make 400 hp at the wheels simply by upping boost but in stock form it only produced 320 hp at the crank. It was fully built and equiped to produce 500 hp in stock form but it didn't come that way from the factory and Toyota couldn't claim that power. This was done with one tiny little modification. The P85D is running the margin limit on it's 1300 amp fuse so it requires a not so trivial modification to get what was originally promised.

But the point you make and the point I make has been repeated by many others in many other threads. This horsepower is beat to death already.

At least we agree that it was probably misleading but I won't even assume at this point that they intentionally were misleading. I think they really intended to deliver on this and that they ran into technical difficulties when they realized the new upgrade contactors which they've been putting in for a while now and the traditional fuse wouldn't handle 515KW. They probably figured they'd go ahead and release the P85D when they did and just fix it in an update.

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It would be nice if there was a dyno able to map the power output of the front and rear independently. Of course we can still verify total power with a P85D L or P90D L dyno (assuming we can solve the issues that dynos seem to be having measuring the power of the dual motors).

If there was such a dyno, you'd have to somehow program the car not to activate traction control when both axles start spinning at different speeds.

 

[Andyw2100]

This part I disagree with you. The optimist in me hopes that Tesla will make this right at some point while I still have a driver's license.

They could go a long way towards making it right by just giving those of us affected the Ludicrous Mode upgrade, instead of charging $5000 plus installation costs for it.

I'm really not sure that we should be celebrating this supposed "discount" that we're being offered. From reading posts here, it sounds like the actual cost of the parts in the upgrade is fairly low--well under the $5K discounted amount we'll be paying. I imagine as the roll out of the upgrades start, Tesla will be constrained both by the ability to manufacture the parts, and also by the ability to install them.

I can definitely imagine a conversation taking place deep behind the Tesla walls in which someone floated the idea of doubling the proposed price for a while, and offering a big "discount" to the original P85D buyers. Shortly after the discount period ends, and depending on supply and demand, Tesla could then have a major price reduction on the upgrade, resulting in the upgrade price settling in at the $5000 price it was going to be originally, which happens to be the same "discounted" price the P85D owners were offered.

Am I being too cynical?

Perhaps the glare off my Piano Black center console is affecting my brain.

 

[MuppetOwl]

If the 1/4 mile numbers from Tesla is correct and the 3.1 sec for 0-60 is correct for the P85D, the 85D should be faster than the P85D at higher speeds to be able to do a 12.5 sec 1/4 mile?

Does it work this way or am I thinking wrong?
If this is correct, Tesla's numbers proves that P85D owners don't get any more hp above 60 mph than the 85D does.

The Motortrend test of P85 and P85D for passing power from 45-65mph shows that the P85D is only 0.1 sec faster than the P85.

 

[Andyw2100]

If the 1/4 mile numbers from Tesla is correct and the 3.1 sec for 0-60 is correct for the P85D, the 85D should be faster than the P85D at higher speeds to be able to do a 12.5 sec 1/4 mile?

Does it work this way or am I thinking wrong?
If this is correct, Tesla's numbers proves that P85D owners don't get any more hp above 60 mph than the 85D does.

I can't answer your question.

But looking at the new chart for the P85D that includes the Ludicrous Speed Upgrade, something else leaps out at me.

The new chart includes only the numbers 259 hp front motor power and 503 hp rear motor power.

There is nothing on the chart to indicate motor power without the Ludicrous Speed Upgrade.

Isn't this a clear indication by Tesla that --BEFORE-- there was a Ludicrous Speed Upgrade, the P85D was supposed to be capable of the 691, since now they are showing new HP numbers, indicating that the motors are capable of additional HP?

If the argument is that Tesla was only showing what the motors were capable of independent of battery and other considerations before, then these numbers shouldn't have changed, right?

 

[stopcrazypp]

All it proves is that the motors will turn into kenetic energy whatever power is shoved into them. Electric motors do that. They'll keep on putting out more and more whatever you shove into them until you reach some limit and they blow up or burnout.

Now they have different higher numbers for each motor with the L update. No auto manufacturer that produces ICE vehicles can claim some motor power that their motor could produce if you upped the boost, increased the air fuel mixture, opened up the exhaust, or intake. They have to specify what it actually makes as equipped. The mid 90's supra was famous for make 400 hp at the wheels simply by upping boost but in stock form it only produced 320 hp at the crank. It was fully built and equiped to produce 500 hp in stock form but it didn't come that way from the factory and Toyota couldn't claim that power.

You can't use ICE analogies on EVs. For an ICE application because of the high energy density of gasoline, it is not power limited by the fuel pump (akin to the inverter) or the diameter of the fuel fuel tank opening (akin to the power limit of batteries). For example you can buy a crate motor and put it in a car and it'll pretty much output that much power, no matter what gas tank you use.

However, for EVs, batteries (and inverters) are commonly a power limiter. You can buy a electric motor (which will have its own power ratings) and it is very common that you can never hit that amount of power with your car because the bottleneck is at the inverter or battery.

I'll use another example with the Swedish site. Now looking at the website closely, there is actually two different power ratings for every single model (P85D excepted, as brian pointed out):
85D: 422 hp, 262 hp front and rear motor power
70D: 332 hp, 262 hp front and rear motor power
S85: 378 hp, 388 hp motor power
S70: 320 hp, 388 hp motor power
http://www.teslamotors.com/sv_SE/models

I don't see any good way to explain why there are two different numbers (one with "motor power") other than that motor power represents what the motor is capable of, and the first number represents what the whole system is capable of. And there is the same pattern of the same "motor power" for cars with the same motor (70D vs 85D and S70 vs S85), but a different system hp number.

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If the 1/4 mile numbers from Tesla is correct and the 3.1 sec for 0-60 is correct for the P85D, the 85D should be faster than the P85D at higher speeds to be able to do a 12.5 sec 1/4 mile?

Does it work this way or am I thinking wrong?

You can only use the 1/4 mile numbers to compare if you factor in the trap speed. The P85D and P85 have similar trap speeds (~115mph). The 85D however has a much lower trap speed at 107mph.

 

[sorka]

If the 1/4 mile numbers from Tesla is correct and the 3.1 sec for 0-60 is correct for the P85D, the 85D should be faster than the P85D at higher speeds to be able to do a 12.5 sec 1/4 mile?

Does it work this way or am I thinking wrong?
If this is correct, Tesla's numbers proves that P85D owners don't get any more hp above 60 mph than the 85D does.

The Motortrend test of P85 and P85D for passing power from 45-65mph shows that the P85D is only 0.1 sec faster than the P85.

85Ds have been logged at 376 KW vs the P85D at 414 KW. So there is a difference but nothing like what the hp numbers said when they were still publishing combined hp for the P85D.

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You can't use ICE analogies on EVs. For an ICE application because of the high energy density of gasoline, it is not power limited by the fuel pump (akin to the inverter) or the diameter of the fuel fuel tank opening (akin to the power limit of batteries). For example you can buy a crate motor and put it in a car and it'll pretty much output that much power, no matter what gas tank you use.

No but the amount of boost and fuel pressure and fuel pump capacity does matter as does the intake and the exhaust all of which ICE manufacturers must bolt to the engine before they run it on a brake horsepower dyno. Manufactures only specify the power that their iCE makes in it's current configuration. There are many crate motors that make wildly different amounts of horsepower depending on what you attach to them. Motors that have turbos have very large differences depending on what boost you run them at and how rich you're willing to map your air fuel ratio under load to prevent pinging/detonation.

Manufacturers never specify horsepower based on what their engine could make but only what it does make as it is configured in that particular vehicle. Haven't I already said all of this before? Like a million times by now?

But in the end, it comes down to how much horsepower is actually made. Notice how the hp numbers jumped up a lot for the Ludicrous mode? They're not displaying combined power of course because doing that is what started these stupid debates, but if what you said was true, then how come they've suddenly change those numbers? If the previous numbers are what the motors *could* make if you gave them enough food, then how come their now saying it's a whole lot more. It means the previous numbers weren't the actual maximum potential of those motors despite their diet.

 

[Matias]

I can't answer your question.

But looking at the new chart for the P85D that includes the Ludicrous Speed Upgrade, something else leaps out at me.

The new chart includes only the numbers 259 hp front motor power and 503 hp rear motor power.

There is nothing on the chart to indicate motor power without the Ludicrous Speed Upgrade.

Isn't this a clear indication by Tesla that --BEFORE-- there was a Ludicrous Speed Upgrade, the P85D was supposed to be capable of the 691, since now they are showing new HP numbers, indicating that the motors are capable of additional HP?

If the argument is that Tesla was only showing what the motors were capable of independent of battery and other considerations before, then these numbers shouldn't have changed, right?

Yes. I don't understand, why the motor power is now 259 + 503. Have the motors changed?

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I wonder, why no car magazine is not interested to pose a one simple question to Tesla; what is the maximum combined battery powered simultaneous power output from motors in stock P85D.

 

[MuppetOwl]

You can only use the 1/4 mile numbers to compare if you factor in the trap speed. The P85D and P85 have similar trap speeds (~115mph). The 85D however has a much lower trap speed at 107mph.

The P85 have a trap speed of 107-108 from when Motortrend and Edmunds did test, and cant find anyone near 115. So the P85 is as fast as the 85D

 

[3mp_kwh]

You can't use ICE analogies on EVs.

Oh, yes you can. He chose to talk about what could be done to a Supra, and how its maker ethically advertised only its as-delivered HP. We could be talking about the thrust of a unicorn passing skittles. The same ethic applies. Anything more is fictional.

This whole thing is academic, because Tesla could provide P85D free "L" mods that reach 691HP, and detune the software to sandbag the original 0-60, and quarter mile, times. Very easily done, with message: "Pound Sand"

 

[stopcrazypp]

No but the amount of boost and fuel pressure and fuel pump capacity does matter as does the intake and the exhaust all of which ICE manufacturers must bolt to the engine before they run it on a brake horsepower dyno. Manufactures only specify the power that their iCE makes in it's current configuration. There are many crate motors that make wildly different amounts of horsepower depending on what you attach to them. Motors that have turbos have very large differences depending on what boost you run them at and how rich you're willing to map your air fuel ratio under load to prevent pinging/detonation.

Manufacturers never specify horsepower based on what their engine could make but only what it does make as it is configured in that particular vehicle. Haven't I already said all of this before? Like a million times by now?

But in the end, it comes down to how much horsepower is actually made. Notice how the hp numbers jumped up a lot for the Ludicrous mode? They're not displaying combined power of course because doing that is what started these stupid debates, but if what you said was true, then how come they've suddenly change those numbers? If the previous numbers are what the motors *could* make if you gave them enough food, then how come their now saying it's a whole lot more. It means the previous numbers weren't the actual maximum potential of those motors despite their diet.

Oh, yes you can. He chose to talk about what could be done to a Supra, and how its maker ethically advertised only its as-delivered HP. We could be talking about the thrust of a unicorn passing skittles. The same ethic applies. Anything more is fictional.

I can buy an LS7 crate engine from Chevy. It is rated at 505 hp, and I can pretty much use a standard gas tank and fuel pump and get that 505 hp.
http://www.chevrolet.com/performance/crate-engines/ls7.html

For an EV, I can buy a AC-150, 150kW (201hp) motor from AC Propulsion. However, if I put it in a Leaf, I will never see 200 hp because the battery is limited to ~80kW (110hp).
https://www.acpropulsion.com/datasheet/AC-150 Motor.pdf

That is the main point I am making. With "motor power", Tesla is advertising the "200hp" "motor power" number above as opposed to the 110hp system horsepower number. And if you see below I have an example of where they have both numbers.

On the subject of increased numbers for the P85D "motor power", it is possible Tesla made some changes to the motor or that after adding the fuses they found that the motors can be pushed further than expected. The way motors are power limited is by how much tolerance they have for operating in higher temperatures (there is a good thread on the Roadster software that showed the limits for the Roadster motors). It is possible to push these thermal limits at the cost of operating life of the motor. It may be possible that given Elon mentioned the new fuse and inconel contactors operate much cooler than before, they can operate at higher current without overheating the motor. Or they have made some changes to the production versions with the release of P90D.

I'll refer you guys to this again about the two numbers being advertised at the same time:

I'll use another example with the Swedish site. Now looking at the website closely, there is actually two different power ratings for every single model (P85D excepted, as brian pointed out):
85D: 422 hp, 262 hp front and rear motor power
70D: 332 hp, 262 hp front and rear motor power
S85: 378 hp, 388 hp motor power
S70: 320 hp, 388 hp motor power
http://www.teslamotors.com/sv_SE/models

How do you guys explain what "motor power" means in the above example (for example 388 hp motor power for S70) vs the first number (320hp for S70)?

 

[legislator]

I find the gear ratio, front vs rear, to be just as interesting. Why can't anyone obtain these? Does the 85D have the same front and rear ratio as the P85D? As the front motor in P85D is smaller (221hp) than the 85D (262hp), the 85D would be faster in high speed acceleration if the gear ratio is the same, considering the back engine only allows 120mph~.

 

[sorka]

I can buy an LS7 crate engine from Chevy. It is rated at 505 hp, and I can pretty much use a standard gas tank and fuel pump and get that 505 hp.
http://www.chevrolet.com/performance/crate-engines/ls7.html

But only if you attach the intake and exhaust that they used to rate that motor on the brake dyno. The LS7 and other crate motors are used in other chevy products that have different ratings for the same motors in different models of cars based on the type of exhaust, shape of exhaust pipes to get around obstacles, type, shape, and size of intake.

When a manufacturer sells a crate motor, they can attach anything they want and rate at the bhp measured. They can also just bypass that testing and give you the bhp it measured when it was measured for an actual vehicle. I've seen manufacturers to both. But that's completely irrelevant here because ........

Manufacturers rates cars by the power the engine actually makes at the motor shaft in that model of car based on how it's configured. Manufacturers often give different ratings to the same motor when sold separately based on what was bolted to that motor at the time. But we're not buying electric motors. We're buying a vehicle that has a horsepower claim as it is delivered from the factory.

Way back in the day, before SAE standards were put in place to prevent this kind of fraud, manufacturers would dyno their motors with open exhausts, intakes, without accessories attached like ac compressors, alternators, and such, and then claim the car made that horsepower even though it didn't. They're not allowed do to that anymore. They have measure the motor with *exactly* what is going to be attached as inputs and outputs.

 

[Andyw2100]

But we're not buying electric motors. We're buying a vehicle that has a horsepower claim as it is delivered from the factory.

It all boils down to those very simple statements for me.

Everything else just muddies the waters. Average people, as I was, looking at the website when I did, and doing basic research on the car, as I did, heard and/or read "691 HP." We understood that to mean that the car would come with, and would be able to make 691 HP.

It's really as simple as that.

 

[Sad]

It's really as simple as that.

Yep.

 

[sorka]

It's really as simple as that.

+1 It's silly of me to get dragged into playing high school debate word games when it's really just as you state

 

[okashira]

I had this figured out 6 months ago:
Endless-sphere.com View topic - Tesla P85D Insane Mode
Calculated 16.1 amps per cell (peak) and 500hp.
Elon says 1300 amps (17.5A per cell) I was only 8% off.

1300 amps * 3.7V * 96S * ~~.90 (eff of inv/motor/gearbox) = 416kW or 500-550hp.
^^ that's at full SOC... cells will sag lower then 3.7V at anything less then 95% SOC.

 

[Andyw2100]

+1 It's silly of me to get dragged into playing high school debate word games when it's really just as you state

No, I don't think it's silly for you to get dragged into the word games, because you understand this stuff really well, and are coming at it with an expert's level of knowledge. This discussion needs that too.

I'm just trying to provide the perspective of the average consumer, which, at the time I made the decision to purchase, I most definitely was, (at least with respect to the technical aspects of how electric motors function.)