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Thread: Put the slicks on

  1. #31
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    The app is "car performance" and I don't think it has an accelerometer, not one that's built into the app anyway. That's why it has the lag time correction built into the app, which when I tested it added almost 1 second to my test.
    Tony

    1955 Bel Air Sport Coupe

  2. #32
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55 Tony View Post
    So if my phone has almost a 1 second too much advance built in, if you took my times and subtracted 1 second off them does that sound more like a good running BBC? One that is capable of lifting the wheels off the ground? I'm not saying that is my time, it's too much of a guess, I'm just curious if it may be in the ball park.
    I don't know why any "advance" would be built into a timer. I can see having an adjustment for sensitivity of the accelerometer. It could be set off just by vibrations if it's too sensitive. What you want to do is have the timer start as soon as the phone senses forward acceleration of some magnitude. It should be able to sense that in milliseconds. Trying to subtract any time would be complete guesswork and imo would be meaningless. If you're curious, use the calculator. But you also really need to know the weight of the car with you in it.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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  3. #33
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    The advance is built in because the GPS sensing movement has a lag time.
    Tony

    1955 Bel Air Sport Coupe

  4. #34
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55 Tony View Post
    The app is "car performance" and I don't think it has an accelerometer, not one that's built into the app anyway. That's why it has the lag time correction built into the app, which when I tested it added almost 1 second to my test.
    The accelerometer would be built into the phone, not the app. I personally don't think that using the GPS would be very accurate since most GPS devices are typically only good to 15 feet and don't update that fast. They're getting better but there's only so much that can be done since the system depends on measurements from satellites. An accelerometer-based app should work better.

    "Car Performance uses the GPS chip (Not the accelerometer) in your phone along with complex algorithms to accurately and easily determine the performance figures for your car. This requires no calibration, no adjustments and is not affected by the elevation or the movement of the phone. All you need to do is get a signal > press start > go! That simple!"

    https://play.google.com/store/apps/d...formance&hl=en
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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  5. #35
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    Quote Originally Posted by chevynut View Post
    The accelerometer would be built into the phone, not the app. I personally don't think that using the GPS would be very accurate since most GPS devices are typically only good to 15 feet and don't update that fast. They're getting better but there's only so much that can be done since the system depends on measurements from satellites. An accelerometer-based app should work better.
    Well as hard as this is to believe, I agree with you.

    I did find an accelerometer on the phone but it only shows something that looks like a seismograph readout. It's very sensitive, holding the phone with two hand it still shows a ripple. Set it on the desk and it then showed a flat line.
    Tony

    1955 Bel Air Sport Coupe

  6. #36
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    Rick stated in #17 above Tony needs to go to a real drag strip and leave playing phone games to the Millennial's. Any real drag racer will tell you .2 or .3 tenths change in 60 foot time is huge.

  7. #37
    Registered Member chevynut's Avatar
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    There's no reason a good phone app won't work and be pretty accurate. Even with GPS for location and a 15 foot error, that's only about a 2% error in 1/8 mile if the clock starts at the right time. That's where the accelerometer plays into it. A 15 foot error on starting is 25% of the 60-foot mark. But anyone who still uses a rotary phone and has never messed with a modern smartphone wouldn't understand that.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #38
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    Quote Originally Posted by markm View Post
    Rick stated in #17 above Tony needs to go to a real drag strip and leave playing phone games to the Millennial's. Any real drag racer will tell you .2 or .3 tenths change in 60 foot time is huge.
    I find it odd that you feel comfortable telling others how they should live their lives. I have no intention of being a "real drag racer". I'm just having a little fun with my car.
    Last edited by 55 Tony; 03-19-2018 at 02:12 PM.
    Tony

    1955 Bel Air Sport Coupe

  9. #39
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    Quote Originally Posted by chevynut View Post
    There's no reason a good phone app won't work and be pretty accurate. Even with GPS for location and a 15 foot error, that's only about a 2% error in 1/8 mile if the clock starts at the right time. That's where the accelerometer plays into it. A 15 foot error on starting is 25% of the 60-foot mark. But anyone who still uses a rotary phone and has never messed with a modern smartphone wouldn't understand that.
    Really Cnut if you only knew how stupid this sounds to a drag racer, a tenth of a second difference in reaction time equates to about a car length on big end. I have won or lost many a race in my day with a MOV of .001 or .0002.

  10. #40
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    Most of the time, the good ole Butt Dyno is great tool.

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