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Clutch adds third of a second

Discussion in 'Technical' started by vfx, Jun 26, 2008.

  1. vfx

    vfx Well-Known Member

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    I had not heard this one before:

    ELON MUSK: That actually is faster than any Aston Martin or any Ferrari currently in production. And that understates the acceleration of the car because a gasoline car 0 to 60 is measured from when the wheels start moving. The wheels only move after you've engaged the clutch. In our case there's no clutch. So if you were to measure a green flag to 60, we'd probably be apples to apples about a quarter second better than an equivalent gasoline car. So our 3.9 is probably like a gasoline car's 3.6.

    from here:
    Extended Interview: Tesla Motors Chairman Elon Musk | Online NewsHour | June 25, 2008 | PBS
     
  2. doug

    doug Administrator / Head Moderator

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  3. stopcrazypp

    stopcrazypp Well-Known Member

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    #3 stopcrazypp, Jun 26, 2008
    Last edited: Jun 26, 2008
    When I heard that on the video I wondered what he meant when he said the Tesla was faster than any Aston or Ferrari. The F430 can get 0-60 in 3.5, the Enzo in 3.14. Evenwhen I heard it, without the exact numbers, I knew the Enzo & F430 was at least in the mid 3s.

    I think what Musk means is if you start the time at when you start engaging the clutch, then a gasoline car that can get 0-60 in 3.6, when measured at the wheels, will probably take 3.9 seconds. Maybe he is talking about reaction time in drag racing, not that sure, since I'm not a drag racer.

    Edit:
    Reading more into it, in drag racing you can jump the gun a little by starting earlier than the green light so that the reaction time is minimized even with the clutch engaging. He does have a point about how 0-60s are measured from when the wheels start moving up to 60, but in racing there is the reaction time from the green flag to getting the car moving, which the clutchless Tesla probably minimizes. But since 0-60 is still traditionally measured from when the wheels start moving, the number should stay.
     
  4. doug

    doug Administrator / Head Moderator

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    #4 doug, Jun 26, 2008
    Last edited by a moderator: Mar 13, 2016
    He said something like "green flag to 60". So including reaction time, and time to work the peddles. I don't know if I believe him, though. Yes, if you were in the Tesla, you'd just floor the accelerator when you saw the flag. Some cars with electronic shifters are pretty fast, though. The Ferrari 430 Scuderia (shown in the recent Top Gear episode) supposedly shifts in 0.06 seconds, 0 to 60 in 3.5 s.


    But more generally, we know Elon has a way of making statements while dropping important qualifiers. (Top gear acceleration comparison as an example.)
     
  5. DaveD

    DaveD EVs Kick Gas!

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    Is the F430 or Enzo currently in production? I ask because Mr. Musk was quoted using that qualifier in his claim.
     
  6. vfx

    vfx Well-Known Member

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    Yeah I think you guys nailed it. He is talking about the time between the green flag (or green light) to go and the wheels moving...

    So I'm sitting at the Christmas tree waiting for the lights to begin I have my clutch is engaged, my car in gear and my revs are high. The green lamp innights and lift my clutch foot.

    How is that different than stepping on the Tesla "torque pedal" ?
     
  7. power

    power Member

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    The only advantage that the "Torque pedal" would have, would be in the areas of modulating wheel spin. Reaction time would be no different.

    light goes out, dump the clutch. :)

    mk

     
  8. just-an-allusion

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    You have to both release your clutch AND stomp your go pedal...with the Tesla it's just stomping the go pedal.
     
  9. GSP

    GSP Member

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    "So I'm sitting at the Christmas tree waiting for the lights to begin I have my clutch is engaged, my car in gear and my revs are high. The green lamp innights and lift my clutch foot.

    How is that different than stepping on the Tesla "torque pedal" ?"

    I think the only difference is more practice is needed to master a good launch. It takes several tries to find the correct engine speed to hold before side stepping the clutch. Too slow and the engine can bog, to fast and you'll get too much wheelspin. The Roadster's traction control will automatically generate just the right amount of wheelspin. All the driver has to do is floor the accelerator.

    However there is reaction time from "green flag" to the driver flooring the accelerator on the Tesla. A skilled drag racer should be able to get the same reaction time in a manual or automatic ICE car, or in the Tesla. So no advantage to the Tesla on the dragstrip, but a nice advantage on the road.

    GSP
     
  10. TEG

    TEG TMC Moderator

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    Some track conditions and tires could dictate that some controlled amount of wheelspin would be helpful. Some highly trained, highly skilled professional racers may reject the idea that electronic traction control is appropriate for the track/strip.
     
  11. SByer

    SByer '08 #383

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    Yeah, but isn't controlled wheel spin really about keeping the engine in the lower chunky part of the torque band? Not necessary for an EV.

    Or are you talking about getting the tires warmed up to bite?
     
  12. TEG

    TEG TMC Moderator

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    Mostly the latter...

    ( The other thing is a cloud of tire smoke tends to be a crowd pleaser. )
     
  13. GSP

    GSP Member

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    I think you're correct that some slip between tire and track produces a faster launch. Traction control (often called "launch control" in this mode of operation) can be programed to provide the optimum amount of slip, and can do this better than even a skilled driver (and *way* better than a typical driver). This only gets better with an electric motor, which provides quicker and more precise torque control compared to an ICE.

    As you say, some drivers may not accept this. I think F1 teams acknowledged the superiority of traction control by installing it on their cars. As a result, traction control was banned in an attempt to make the races more interesting.
     
  14. power

    power Member

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    EV vs piston engine is pretty close as far as torque available at power dump.

    most engines are rev'ed to 3k and the clutch is dumped. gas pedal management as well as clutch release dictate the slip of the tires for optimal traction and acceleration. with an EV, there is only one pedal, as this same torque is available from a dead stop. only one pedal is needed to modulate the power application. this might be simplier, but in the skilled hands of a racer, not a huge advange.

    mk

     
  15. roopocket12

    roopocket12 Member

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    #15 roopocket12, Jan 14, 2010
    Last edited: Jan 20, 2010
    i agree tha to be able to achieve good acceleration, there should be good pedal management and clutch release. i believe this project is a good innovation to the electric vehicles considering that it is estimated to deliver the speed greater than ferrari and aston martin
     

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