Playing around with VBOX Sport.... 0-60 times...

Going to need to get an external antenna. It won't lock on underneath the windshield. Mounted to the side window half way down, all other windows down, and the pano roof open, I'm able to lock 7 or 8 satellites, but I don't want to leave it like that all the time. It's good enough to start playing with.

I did a few 0-60 runs from 76 down to 74% SOC. They ranged from 3.47 to 3.52 without a 1 ft rollout. With the rollout, the standard way of publishing 0-60 times, that 3.47 is a 3.21. So pretty good for not fully charged.

I still can't figure out how to generate the wheel hp channel. The instructions:

Power, Torque and RPM Calculations - Racelogic

don't match the actual software. The instructions say to used the "VBOX Tools" software but I can't find any such software. I only have the "Performance Box Tools" that came with it on the sdcard and match what's also available for download in the VBOX Sport section.

MS is P85D with 19" wheels.

0-60 times will be slightly....ever so slightly slower than they should have been given all the windows were open so the drag was more.

On the glass of the rear hatch, it's picking up all the satellites as well as without obstruction.

For those of you with the VBOX sport, how solid is your longitudinal accelerometer reading?

Doing some more testing, I'm convinced this unit is defective. Sitting on my desk with no vibration, the longitudinal g reading jumps around like crazy while the lateral g reading is steady as a rock.


It only moves if I actually move the vbox unlike the longitudinal reading which jumps around even when steady on a solid surface.

The dark gray is LongAcc but the vbox tools export doesn't do a very good job exporting graphs.

So apparently the VBOX doesn't use solid state accelerometers to calculate g force. It's using the GPS itself. I'm working with race logic to figure out why my readings are so unstable. It could be reflections from stuff inside the car. But I got the same readings on the grass outside under a clear open sky with 10+ satellites locked. However, that ground is high in iron content (red clay) and could be causing reflections as well.

I could also just have a defective unit.

Got my external antenna today which produces more stable Doppler readings than the vbox mounted inside the cabin. Speed is determined by delta in position but acceleration is determined from the Doppler shift and this is very very sensitive to anything that can bounce the gps signal. The g sensor reading was just too unstable when the reading was taken inside the MS.

The readings are also more stable at night than during the day.

I did one test run tonight at 65% SOC.



The REST KW reading peaked at 375 KW.

Before any conversion losses 375 kw = 504 hp with a max reading of 455 rear wheel hp. This translate to a mere 10% total loss from the battery to the time it gets to the wheels which is less than the typical drivetrain loss from an ICE driveshaft to the wheels alone and the P85D is AWD to boot. Given how few drivetrain components there are from the drive shaft to the wheels in the Telsa compared to a regular ICE going through a flywheel, transmission, torque converter, transfer case, half shafts, and diffs, it's not suprising the that Tesla is so much more efficient. We can't know where the distribution lies, but I'd guess 7% mechanical drivetrain loss and 3% electrical conversion losses.
This data was acquired with a VBOX Sport and an external antenna mounted on the panorama roof. GPS signal stability is better at night so that's when I did the test. I'll be using software to determine optimum test times for lowest DOP (Dilution of Position) based on GPS position configuration to get the most stable signal possible. The REST data for this run was acquired using the iOS app PowerTools.

I'll add data for 10% SOC increments over the next week or so.

WarpedOne said:

Now this is how you do it!

Regarding wheel HP ... it would be best if you could weigh the car before taking measurements, including you and any passengers.
With correct weight and speed chart, it will be possible to produce wheel torque and power charts.

If you can fine places where you could reach top seed (150?) that would be some awesome data to have.

Click to expand...

On the list of things to do. There are several public truck scales open to the public near by that people take uhauls and Penske trucks to. For the graph above, I used 5100 lbs.

E39_S62 said:

I have used a few of those truck scales before and they vary a bit. They may be accurate for the big trucks who are looking to see approximate weight distribution and total weight, but not for this. I have weighed my BMW on those scales and then put it on some intercomp race scales that a friend has at his shop and there was over a 400lb difference.
400lb isnt anything to the truckers, but 400lbs of a 4000lb car is a 10% error

Click to expand...

You are indeed correct. After doing some research, the truck scales, even the ones meant for moving vans will not be anywhere near accurate enough. The published specs on the P85D curb weight are likely to be far more accurate.

I'm going to have to find an automotive racing scale instead. It won't prevent me from doing the runs and collecting data since the weight is applied to post processing.

Here's one for a regular S85 at 84% SOC. All conditions the same again. Flat straight open road with rooftop mounted antenna. For the weight of the MS I use 4630 + my 200 lb weight. This car is a stripper. There are no options. It has air but I don't think coils were an option at that time. No parking sensors, rain sensing wipers, TACC, power liftgate, panoroof, premium sound, etc. Still the weight is probably pretty close:



Power peaks at 375 at the wheels. This is very close to other regular S85's that have been dynoed before despite the 362 hp claim. The base MS produces quite a bit more power than Tesla claims. The P85 dynos around 430 at the wheels.

Power hardly varies at with SOC between 50 and 90%. It may below that but I haven't tried it. Unlike the P85D which progressively lowers peak power as SOC goes below 90%.

Peak g's are 0.531 and remain amazingly constant from 6 MPH to 50 MPH. This is clearly software limited as peak power doesn't occur until 50 MPH. If it wasn't limited, it would pull more g's at lower speed.

0-60 is 5.04 seconds which is 0.36 better than Tesla's claim. This is with a 1 ft rollout. Without the rollout 0-60 is 5.456.

For comparison, Liz's dyno run:


http://www.teslamotorsclub.com/show...no-Video/page4?p=330641&viewfull=1#post330641

showing 376 rear wheel hp.

Updated using 5136 instead of 5100 lbs:



I'll start adding these for other SOCs next weekend when I have my car back.

Here it is for 80% SOC on the P85D:




0-60 was 3.159 with the 1 ft rollout and 3.516 without the rollout.

Peak power from PowerTools via the REST api was 389 KW at 49 MPH. The vbox graph shows 482 rear wheel hp. This was on flat level ground with very little breeze. I repeated the run in the other direction and it was within 1 hp of the same result.​

About to go out and do the 90% one. Just charged to 92% so it will be down to the top of 90 or 91% when I get the 3 miles or to the test location.​

kirkbauer said:

Can anybody help me understand the effect of the rollout? Basically are you saying it takes almost 0.4 seconds for the P85D to move the first foot?

Click to expand...

Correct. 0.357 seconds to move 1 ft.

- - - Updated - - -

With 90% SOC:



498 hp at wheels using 5136 lbs.

So clearly we're at odds with the two dynos that were performed on Dynojet dynamometers. This instrumentation of an S85 shows very similar to if not exactly what other S85s show on a Dynojet but not what other P85Ds have shown on an AWD dyno. Given that P85s dyno consistently at 430 to 436 at the wheels, the P85Ds that dynoed in the same range had some sort of issue.

REST KW readings were 409KW. I did 3 runs from 92% down to 89% and never did see 414KW like I did before at 90%. It's been a few thousand miles. Maybe the battery has changed. Maybe the new 250 firmware dialed it down just a tiny bit. Not sure.

But 409KW = 548 HP. At the wheels 498 / 548 = 9.1% loss from KW reading to wheels which has been pretty consistent from one test to another at different SOCs.