1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Ice-off neutral over 64mph--MG1 did not explode

Discussion in 'Gen 2 Prius Technical Discussion' started by efusco, Nov 30, 2008.

  1. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    Can't tell you much more than the title says.

    In a moment of inattention going down a fairly long steep hill that I'd entered a Neutral glide with Ice-off I exceeded 64mph breaking the theoretical 62mph/10,000 rpm barrier for MG1 under those conditions.

    And nothing happened. I was not on the proper screen to see what rpm MG1 was actually at on my CAN-View. No warning lights, no smoke no screaching, nothing happened.

    AFAIK I'm the first/only one to post such a situation and I'm just getting it in the archives for future reference.
     
    #1 efusco, Nov 30, 2008
  2. EZW1

    EZW1 Active Member

    Joined:
    Aug 20, 2008
    722
    80
    7
    Location:
    Phoenix, AZ
    Vehicle:
    2016 Prius v wagon
    Model:
    Four Touring
    There is always a design margin. A good engineer allows at least a 10% margin, so if this is the case in the Prius, it should do 11,000 rpm before it flys apart. Good to know one can get at least to 10,000 without trouble.
     
    #2 EZW1, Nov 30, 2008
  3. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    At least this time with Evan's Prius. ;)

    Tom
     
    #3 qbee42, Nov 30, 2008
  4. ken1784

    ken1784 SuperMID designer

    Joined:
    Dec 18, 2003
    2,943
    1,378
    67
    Location:
    Yokohama, JAPAN
    Vehicle:
    2010 Prius
    Model:
    N/A
    I did same thing last month. :)
    Drove up to 102km/h(63.4mph) actual or 108km/h(67.1mph) displayed speed, and the calculated MG1 speed was 9333rpm.
    Nothing happened.

    Ken@Japan
     
    #4 ken1784, Nov 30, 2008
  5. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    If you have not reset your CAN-View take a look at the max/min screen to see what it says.
     
    #5 TheForce, Nov 30, 2008
  6. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    good thought, I forgot I had that option. I'll do that in a little while.
     
    #6 efusco, Nov 30, 2008
  7. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    Good call -8900rpm & + 7800rpm were the min/max. Interesting. It seems that the formula predicted number are off.
     
    #7 efusco, Nov 30, 2008
  8. alanh

    alanh Active Member

    Joined:
    May 22, 2007
    1,175
    99
    0
    Location:
    Phoenix, AZ
    Vehicle:
    2007 Prius
    I think there was some discussion here that the Prius would spin the ICE even in neutral to prevent MG1 from overspeeding. I can't find the thread right now, though.
     
    #8 alanh, Nov 30, 2008
  9. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    We wondered if it might kick in the ICE, but nobody's seen that happen.
    It definitely did not kick in the ICE in my experience today.
     
    #9 efusco, Nov 30, 2008
  10. Bob64

    Bob64 Sapphire of the Blue Sky

    Joined:
    Apr 9, 2007
    1,540
    93
    0
    Location:
    Virginia
    Vehicle:
    2007 Prius
    Model:
    N/A
    Alanh, I believe your confusing it with Drive.

    The only way to get the prius to 64mph in neutral with the ice off is to get into neutral with the ice off before you hit 41mph, and then accelerate to 64mph (by gravity).

    Neutral "locks" in the state of the engine at the moment in which you activate it.
     
    #10 Bob64, Nov 30, 2008
  11. narf

    narf Active Member

    Joined:
    Mar 15, 2005
    611
    45
    4
    Location:
    Colorado
    Vehicle:
    2016 Prius
    Model:
    Four Touring
    I did a little scangauge test a while ago regarding this.
    What I found was that if the ICE was already running when put in neutral (i.e. at over 41 mph), the ice rpm would continue to spin up correctly in neutral even though no fuel was being used, no matter how fast you ended up while coasting downhill.

    On the other hand, if you put the car in neutral while the ICE isn't running (in my example, 38MPH), the car will accelerate well over 42 MPH without the ICE rpms spinning up. I ran it up to 50 MPH before running out of space and nerve, and still registered 0 rpm on the scangauge.

    I'm guessing here, but I suppose that would make it less than advisable to switch to neutral if you are starting under 41 mph and planning on coasting up to high speed.
     
    #11 narf, Dec 1, 2008
  12. alanh

    alanh Active Member

    Joined:
    May 22, 2007
    1,175
    99
    0
    Location:
    Phoenix, AZ
    Vehicle:
    2007 Prius
    I think this was the post I was thinking of:
    Although it only mentions MG1/2, I think the last point implies that it will start whatever is necessary to avoid destroying MG1 even in neutral. It might not "start" the ICE, it may only spin it ala warp stealth.
     
    #12 alanh, Dec 1, 2008
  13. ken1784

    ken1784 SuperMID designer

    Joined:
    Dec 18, 2003
    2,943
    1,378
    67
    Location:
    Yokohama, JAPAN
    Vehicle:
    2010 Prius
    Model:
    N/A
    FYI,
    Attached graph is my log.
    During my down hill driving, I shifted to N at 1:21'45", then shifted back to D at 1:23'59".

    Ken@Japan
     

    Attached Files:

    #13 ken1784, Dec 1, 2008
(You must log in or sign up to post here.)