dhanson865
Well-Known Member
FORD'S MUSTANG COBRAS WILL GET HORSEPOWER FIX
and then later
and then
apparently there was aluminum "flash" aka junk that wasn't trimmed in the manifold and
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Tesla blog post: AWD Motor Power and Torque Specifications
- Thread starter dsm363
- Start date
-
- Tags
- Driving Dynamics Model S
FORD'S MUSTANG COBRAS WILL GET HORSEPOWER FIX
and then later
and then
apparently there was aluminum "flash" aka junk that wasn't trimmed in the manifold and
Why be so loose with facts? Ford advertised car as having hp *less* than specified. Tesla shipped cars that have hp exactly as specified, in strict accordance with the only existing Regulation dealing with EVs, ECE R85. How are these two situations the same??
Wait a second, so if you place a P85D on a dyno, it WILL produce the advertised 691hp?!?!! Whoa, my mistake. All this time, I had incorrectly assume that the P85D was incapable of ever producing anything close to 691hp. My apologies!!!
Summary: Cars must be expected to hit their stated acceleration times as that is the tangible and functional result of the powertrain. Other items like horsepower and torque are means to the acceleration end. Comsumers of EVs have to understand what their car can do and what it cannot. There are so many details that could be explained in terrifyingly boring detail to only come to the conclusion of "How fast can my car go?" What seems to make sense to me IMHO would be a graph which shows the expected acceleration times at stated environment (ambient temp) and vehicle dynamic conditions (battery SOC, inverter, stator temp..etc) where X is speed and Y is time and Z colored lines which represent major battery SOC bands (100 to 90%, 89 to 80%...etc)
Ah, found some details now, thanks! And it does show up on wiki here: https://en.wikipedia.org/wiki/Ford_Mustang_SVT_Cobra#1999.2F2001
Also found some of the '50' letters that prompted the recall and shipping/selling hiatus:
http://www.atomicfrog.com/mirrors/www.blueovalnews.com/letters_99cobra_problems.htm
The glaringly obviousness of this is that the car would not achieve the stated 0 to 60 times as tested by Car and Driver it was actually slower than previous models:
http://www.caranddriver.com/reviews/1999-ford-mustang-svt-cobra-tested-review
Yes.
But you have to find a dyno that is capable of reading power output at least 10 times per second with resolution of 1:1000.
You don't know what I'm talking about? You are not the only one...
Took about a second to google it. The below has "Up to 1,000 recordings per second (per channel)" which exceeds your requirement by 100 times and is capable of measuring thousands of HP. Let's strap a P85D and measure it. How about it?
Chassis Dynamometer Specifications
Here's another one that's accurate to within 1 microsecond which is a millionth of a second. Surely that would meet your requirements.
Dynojet Automotive Chassis Dynamometer Model 424xLC2 All Wheel Drive
Last edited:
I know it is a fact that does not apparently fit your version of reality, but P85D was advertised as having 691 motor hp, rated by Tesla according to ECE R85, the only Regulation applicable to EV. This regulation directs manufacturers rate EV drive train without taking into account potential limitation of the propulsion battery. So if you put P85D drivetrain on a dyno and test in accordance to the protocol established in international Regulation ECE R85 it will produce exactly the hp it was advertised to produce.
You are playing loose with facts and *should apologize*.
I will as soon as I see a stock P85D produce 691 HP (adjusted for drivetrain loss) on a dyno. Until then, naahh....
Nope, it would not.
It may even read 1.000.000 times per second but it still wont recognize a 10 ms long 691HP kick out of constant 550HP push.
Those drums weigh some serious number of pounds (some come in thousands) and thus need some serious joules to speed up. 10ms long power-kick does not carry enough energy for those drums to accelerate enough.
Does that mean the motor did not produce 691HP? No, it means dynos cannot measure such short power bursts, they measure steady state. 10 second acceleration run is steady state for them, 10ms power kick is transient that gets averaged down to battery power.
A dyno capable of measuring at the microsecond level is not accurate enough to measure something at 10 milliseconds? No offense but now it sounds like you're making up stuff as you go along. Good luck on your future endeavors...
Hpham007 is right, if the dyno is accurate and precise enough to measure and report the change in kinetic energy of the drum 1,000 times per second to enough decimal points, it will catch the 691HP 10ms pulse. It does not matter how much the drums weigh.
Course I doubt there is a Dyno out there that would be that precise, as there is no point to it.
A far easier, and more realistic way would be to just read the input power to the motor, as there are tools that can do that accurately and precisely enough. Still pointless though.
Seems obvious to me if the car didn't hit the numbers, they should have just increased the rollout, I hear Democratic Republic of Congo uses a 10ft rollout that should do it. It would have been far cheaper than fixing the cars.
- - - Updated - - -
Yes and we then get back to the R85 argument.
My view FWIW is Tesla were late on the X.
They needed some good press to bolster the share price.
They had got some seriously good numbers out of some mule S cars running the drive train for the X (without real care for longevity.)
Elon thought OK this will make some good press. What angle can we come up with.
"Hmm I used to have a Mclaren, that car was a legend, let's go for that as an angle" the D stats where reverse engineered from there.
Everyone would rightly point out that a Mclaren had 627bhp would smoke a Model S (in a game of top trumps). So the number had to be higher than the F1.
Tesla then bent every stat they could to fit the story.
Look the car is cracking. It's just a shame the likes of George Blankenship aren't still around to stop this sort of mess happening.
And there would be flying pigs if only pigs would fly.
Drum weight is the main problem here - it accumulates energy while speeding up. Heavier the drum, more energy it "eats" while speeding up for say 1%, lighter it gets, mores sensitive it will be as it will need less energy for same 1% change.
There were 'old' intertia-based with drums weighing in excess of 3000 pounds. Modern dynos are more sophisticated, using eddy current brakes etc but they still need to be strong enough to carry a 3000 pound vehicles. So they are still build of steel and have considerable dimensions and weight. And then there are also rotating parts in the car eating their part of that power burst.
I'd be glad if anyone can show me that there really exist some commercial dynos that can measure 10ms long 691HP burst at 50mph out of 550HP baseline. Joined hands in united "you are wrong" is no proof.
It all boils down to how long it has to output 691HP for one to be satisfied. 1ms, 1s, 1hour?
I consider this incorrect. They shipped motors that can handle the horsepower specified, on a lab bench. The cars do not produce the specified horsepower.
- - - Updated - - -
Apparently you've confused yourself. It happens a lot.
In the first quote, you indicated that the P85D is shipped with the exact horsepower specified. This implies that Tesla actually stated the horsepower of the P85D.
In the third quote, you indicated that the P85D was advertised with motor horsepower.
It seems the confusion is that you mixed up "advertising the horsepower" with "advertising the motor horsepower". It's a common mistake. Apparently even the experts in this thread mix it up.
That's just not true. I've quoted nothing out of context.
This is from Annex 6: "Method for measuring net power and the maximum30 minutes power of electric drive trains "
Item 1 of table 1 which the above sentence is referencing is "DC Voltage Source". Therefore it's to be installed in the same position as in the vehicle. Nothing you've referenced says it can be an arbitrary DC voltage source. If so, then you could fix that voltage source to provide enough current such that attaching electric accessories, which you do to measure how they impact the rated power, would be pointless.
Also, I never said that the the drivetrain could haven't multiple motors. I just said there's nothing in R85 that says you can add up the power from each motor into one number. Even where Tesla lists that they tested in accordance to R85, they don't sum up the motor powers. They are listed separately.
But, let's just assume that you're right in your interpretation, the following is still true:
- Tesla stated "691 hp motor power" on their website in multiple places. It did not state anywhere that "hp motor power" meant something other than hp produced by motors. There was no asterisk next to the horsepower spec stating that this is not actual horsepower produced by the production vehicle.
- The only place ECE R85 was referenced was inside the owners manuals and even these didn't contain the that reference until after the P85D was already shipping. Are we to expect that prospective buyers doing their research are supposed find this reference first in the owners manual?
- The subsystems page in the manual lists individual motor powers and does not add the front and rear motors together. In fact, if you add up front and rear motors, you get 728 hp, not 691 hp.
- Publications for over a year now have been publicizing 691 hp, not "hp motor power". Why hasn't tesla corrected them and why are they all still quoting 691 hp when the car only makes 480 to 555 hp depending on state of charge?
- The sales people repeatedly stated the P85D makes "691 horsepower" without ever adding the term "motor power".
- Elon Musk himself has been quoted as saying the P85D has 691 hp and did not use the term motor power. He's also been quoted as saying the P85D has 50% more power than the P85.
- If they were going to list a combined horsepower number, they had an obligation to list the power that the P85D actually makes. They do for the other Model S trims. In addition, since the P85D is the only Model S to lose power as the SOC declines in it's normal daily driving range, they should have clarified that the 555 hp is only at 90% SOC or greater and that below that, power will decline as charge declines. This is not true on the other Model S variants until you get much deeper in to charge state.
- Ignoring repeated multiple letters and emails over MONTHS asking for clarification about the horsepower rating. We get responses for everything else we ask but those that inquired about this got nothing. If they were being so above board about this with nothing to hide, how come they refused to respond to the question of "why is my car only making 480 to 555 hp (depending on SOC) when it was advertised at 691 hp"?
- Just because they test according to R85 to arrive at motor power ratings doesn't mean they get to use that in place of actual horsepower specified. Nowhere in the regulation does it state you can substitute horsepower rating of the vehicle with motor power capability of the drivetrain (with a power source not supplied). These are two entirely separate things. One is the actual horsepower produced by the vehicle. The other is an irrelevant specification that can't be reached with the shipping battery. It's only possible value would be knowing your drivetrain could handle more power if a battery with more power became available in the future.
Answer me these questions honestly:
Do you think the average consumer when they're looking up P85D specs and they see "691 hp motor power" will think it means something other than horsepower produced by the vehicle at some point?
What if they're relying on popular trustworthy consumer publications where they all say "691 hp" rather than "691 hp motor power"?
What if they're a P85 owner that knows their P85 makes "417 hp motor power" but it turns out that it really makes much more and such Tesla under promised and over delivered. Will this give them confidence that the P85D really makes the 691 advertised hp or should they expect to only get 555 hp, only some 80 hp more than the P85.
You keep saying Tesla was required to test with ECE R85. Well not in this country they weren't and even if they were in Europe, the drivetrain power rating is there for a legal listing requirement, not as an actual declaration of vehicle horsepower. They certainly weren't required to list "691 hp motor power" on their US website. Is there anything wrong with them testing with ECE R85 and listing drivetrain capacity? Not at all. But there is something seriously wrong with them trying to pass that off as horsepower produced by the vehicle(remember nowhere where 691 hp was stated did it say *tested in accordance with ECE R85 and that this is not the vehicle power actually produced in this configuration).
- - - Updated - - -
Actually, it's far far worse than that. SAE GROSS used prior to 1972:
And then in 19872:
Since Tesla doesn't have mechanical accessories, drive belts, intakes, exhausts, and isn't effected by atmospheric pressure, temperature(mostly), and humidity, this standard doesn't apply.
However, without even reading through the rest of this thread yet, I'm willing to bet good money that someone will tell you that because these factors don't apply to EVs that there's no way to make an apples to apples comparison of an EV drive train to an ICE drivetrain. Of course that would be a bunch of nonsense. You can still measure horsepower of EV drivetrains but their output won't be restricted by most of the items listed in J1349.
Now the reason it's far far worse than you think is because tesla is not stating actual horsepower produced under any standard, not even under ECE R85. Instead, they are stating the combined horsepower capability of two drive units but only if you supplied 525 KW (691 hp) rather than the 414KW *actually supplied*.
Most of us who have an issue with this would have been *thrilled* if the P85D produced 691 hp at the battery before conversion losses and before drain from accessories.
- - - Updated - - -
But it doesn't direct them to lie about the actual horsepower produced.
- - - Updated - - -
A 1 ms 691 hp burst through P85D's drivetrain would not measure on any dyno no matter how fast it sampled. The inertia the drive unit, reduction gear, diff, drive shafts, and wheels would absorb such a short burst and it wouldn't even be a blip.
But are really back to "prove the P85D doesn't make 691 hp"? Tesla has already admitted it doesn't which is why that debate died out over a month ago.
- - - Updated - - -
I think that's a pretty astute observation. But I take this as more evidence that this spec is just badly worded and probably full of errors. 2.3.1 says the items in table 1 are to be fitted as in the vehicle but clearly an auxiliary bench fan can't fall into that.
I spent 10 years writing software for manufacturing and automated testing devices and read through dozens of specs like this and there were always errors. What's worse is that when you asked the spec provider/author for clarification, they'd acknowledge the error, tell you how to interpret it, and then not actually rev the document.
Last edited:
I see no resolution to this disagreement, only each side endlessly repeating its arguments. I think Tesla is not going to take any action or admit error. I suggest that you guys take a break. You've all made your points, over and over again, and you are now going around in circles.
I am not saying this as a moderator, I have no authority over this particular subforum. I am simply suggesting that everyone cool off for awhile. But of course you can ignore my request and continue arguing...
I am not saying this as a moderator, I have no authority over this particular subforum. I am simply suggesting that everyone cool off for awhile. But of course you can ignore my request and continue arguing...
Nigel Tufnel
Member
I think all posters on this thread who've taken a consistent position on the issue should be required to switch sides and start arguing in favor of the other point of view. It would likely be entertaining and probably therapeutic for those involved.
Of course anyone not complying should be banned.
Of course anyone not complying should be banned.
Thank you for the alert. To clarify, they shipped cars. Each of them included a drive train with two motors and two inverters, tested as an overall assembly according to ECE R85. Tesla's specifications reflected the above.
Similar threads
- Marketplace listing
- Question
