I have tuned many cars on dynos and know they limitation. Also I have tried to dyno Teslas, its not possible to get correct. The roller dynos don't support 2 engines with different output and Dynapack is not possible to use because of the gear ratio and does not support different gear ratio front and back.
If the 430hp numers is correct, that is the same as P85 as some have dynoed the P85 to. We know for a fact that the P85D is faster also at higher speeds so it must put down more kW. At higher speeds the difference is not very much but it is there. The biggest different is how fast the P85D ramps up the power since it is not as traction limited as P85. Also none of the roller dynos I have tried are able to not slip if you have max power from a standstill, so they are not able to measure power where the P85D have the most.
The HP number for the P85D I think is somewhere around 500-520
Any dyno where you can lock the two drums together to simulate the ground is capable of testing a D. It doesn't matter if it has one motor, two motors, or a million motors. I don't know about the Dynapack, but the MD-AWD-500 Mustang Dyno is appropriate for measuring the horsepower of a Tesla D. The Dynojet is also appropriate as long as you engage the Linx system which locks the two drums together. If you don't then the two axles could spin at different rates which would invalidate the test. An example of when you wouldn't use the Linx system on the Dynojet is for a a 4wd vehicle that has already locked it's transfer case and are forcing the axles to move in unison. Minor differences in wheel/tire diameter would cause slippage on a dyno that has it's drums locked toegether. In this case, for a 4wd vehicle, you'd disengage the Linx and each drum has it's own PAU. You can't drive a 4wd vehicle in 4wd mode on a smooth dry solid surface. You can only drive in 4wd mode in mud, snow, gravel, sand, etc.
The Mustang Dyno has one PAU and treats both drums, which are linked with a toothed built, as one surface as if you were testing on the ground.
A more in depth discussion:
Need 85D volunteer in Sacramento area for a dyno test......
Regarding not being able to get an accurate reading due to slip: Max torque occurs early on at around 12 MPH but max power doesn't occur until 36 MPH long after torque has fallen *way* off. The one public dyno where the wheels slipped was right around 10 MPH long before max power would have been achieved. By the time peak power rolls around, we're far off from having any issues with slip.
There's only one P85D run posted on a Mustang Dyno. It's not enough. There could have been any number of things wrong that could have lowered the results. The car might not have been charged very high. There's over a 50 hp difference between 100% SOC down to 50% SOC. The P85D could have had some issue. It might have been overheated and pulling back power. The dyno could have had a problem. Maybe it was really cold and the operator corrected for atmosphere which you can't do on an BEV.
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At some point in time, it was.
I had a P85+ loaner for a week and that video represents exactly what I noticed in the difference. The P85D was faster in a roll on but only barely. Enough to notice.
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I find it quite telling that this thread has gone from arguing about whether or not the P85D makes 691 HP to arguing about how much less than 691 HP the P85D makes.
555, 550, 520, 500, 460, 430, 413...I'm no mathematician, but even I can determine that all those numbers are quite a bit less than--not more than or equal to--691.
Well, 555 is sort of the theoretical cap isn't it. It can't make more power at the motor shaft than is output by the battery. So the real debate should be how much is lost in conversion from the battery, through the inverter, and finally through the motor to the motor shaft(s)
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- however this would be easy for Tesla to put to rest. Just give us the official hp number for the P85D
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Um, they could NEVER do that unless they want to pony up L upgrades for free for every single P85D ordered prior to them removing the 691 combined number from their site.
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Yes, but doesn't it assume the normal peaks, of ICE HP. The area under the Tesla's torque curve, given its peak, is guaranteed to be bigger than ICE vehicles of similar spec. If Vbox assumes a slow run-up, on the way to peak HP, and then backs into resulting times, those times will be longer by virtue of the time it took the ICE it assumes you're driving, to make its peak HP. For an EV, the HP tails are likely fatter and don't require the same peak, in order to deliver an equal time. I can see this logic in advertising the P85D, and how it would abuse reality.
It makes no such assumptions. It calculates how much power you need to move from speed x to speed y in z time with a given mass. Period. It doesn't care if that's an ICE, EV, steam engine, or Fred Flinstone pounding his feet on the ground.
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Perhaps. But it's not like ICE vendors are the paragon of openness. Peak HP is a pretty meaningless figure without a LOT of qualifications... what point in the drive train it's measured, what other parasitic loads are on the engine, the shape of the power curve, transmission design and performance, etc... EVs, as you note, are a really different animal and so comparing peak HP on an EV to and ICE is apples and oranges as a measure of performance.
Actual vehicle performance (with a rollout or not) is far more meaningful because it filters out all (most?) of the BS. 0-60, 0-100, 1/4 mile, etc...
On some of the more popular measures (0-60, starting torque and "holy $hit factor") my P85D performs very similarly to or better than a 700HP ICE vehicle. That's good enough for me. And if somebody asks I have zero issue giving them the 691 number. Almost nobody digs into the details enough care about the minutiae that is being flogged to death here.
Really? Name *ONE* ICE car that produces 700 hp that is the same or slower than a P85D from a 50 MPH roll.
Just compare it to a 700hp 4500 lb Hellcat:
The Hellcat is only 10% lighter but it's accelerating 50% faster almost the entire time after 60 MPH.
Heck, even an Audi RS7 in a 50-70 MPH pass crushes a P85D and the Audi only has 560 hp. It might be lighter, but on paper, the P85D is supposed to have the superior power to weight ratio but in fact is far worse power to weight ratio than the Audi.
The start of that graph is *why* the P85D goes like stink to 60 because the power it does generate it generates sooner hence the insane torque low down and the crazy g's that are front loaded.
Here's one with a P85D at 80% first compared with an S85 at 84% second:
There's only about a 100 hp difference between the S85 and P85D at the wheels but look how much *MORE* power the P85D makes early on. It's all about the power put down integrated over time under the curve, not peak power. This is important when you're talking about taking off from a standstill rather than a 50 mph rollin where you're able to make peak power immediately in the P85D vs almost immediately in an ICE(might have to downshift). The S85 doesn't even make it's peak until 50 MPH while the P85D is flattening out after 36 MPH.
