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Dyno Testing with PerfExpert

Discussion in 'Model S: Driving Dynamics' started by SomeJoe7777, May 2, 2015.

  1. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

    Mar 28, 2015
    Houston, TX
    I found an interesting app in the Google play store the other day - PerfExpert.

    Note: I am not affiliated with them in any way, I just thought it was a good app and purchased it. I'll not post the link here, but if you search the Google Play store, you'll find it.

    I set it up, did the calibration procedure (read the guide! it's not exactly straightforward), and entered all the parameters for the 85D to do timed runs and dyno runs.

    Here's the result of a dyno run. Relevant parameters:

    SOC: 71%
    Software: 6.2 / 2.4.188
    Outdoor temperature: 82.6 F
    Pressure: 14.8 psia
    AC: On
    Range Mode: Off

    Parameters entered into Perf Expert:

    Car weight: 4630 lb (from manual - curb weight)
    Additional weight: 240 lb (205 lb for me, 35 lb of other items in frunk)
    Engine displacement: 2 L (had to enter something, not relevant for the 85D)
    Wheel Dimensions: 245/45R19 (stock Michelin Primacy on 19")
    Cd.A: 0.24
    Transmission: 4WD
    Final drive ratio: 9.73:1
    Measure beginning rev: 1200 RPM (equates to 9.85 MPH with these tires)
    Pitch: 3 deg / G
    2nd Gear Ratio: 1.0:1 (required for ICE measurements, N/A for 85D)

    The dyno graphs and summary are here:

    I had to let off at about 80 MPH on this run, didn't have enough room to continue. Ideally would have done full 1/4 mile.

    Some caveats with the data presented on the website: 1) Car weight and additional weight shown in the link is listed in Lb, but the web site is presenting the values in Kg. In the app on the phone they show correctly. 2) Engine displacement shown in the link is multiplied by 1000 (shows a 2000 L engine :smile: ). Shown as 2 L in the app, matching my entry, although completely irrelevant for the 85D.

    The surprising result is the peak power of 361 kw (484 HP), a full 62 HP over Tesla's stated rating of 422 HP for the 85D. Also as we can see and expect, torque is constant at about 535 ft-lbs from start to about 4500 motor RPM (about 37 MPH), then begins to taper.

    I'm amazed that the app can get this accurate using only the accelerometers in the phone. My phone is a Samsung Note 4, by the way, running Android 5.0.1.

    I would love for someone to get an accurate run with this on the P85D and see if the peak power is actually coming close to Tesla's stated 691 HP.

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