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Testarossa Rev Range

Discussion in 'Boxers/TR/M' started by oo7ml, Sep 7, 2020.

  1. oo7ml

    oo7ml Karting

    Dec 4, 2018
    72
    Dublin, Ireland
    Full Name:
    Mark
    #1 oo7ml, Sep 7, 2020
    Hi,

    I only picked up my Testarossa a few days ago and the car has been driving great.

    Yesterday, I noticed that the rev counter was a little slow or lazy but the car itself and the engine was fine... the rev counter was more lively the first few days of ownership.

    I have brought the car for another spin to record some of the readings in various gears.

    Rev Counter Readings

    1st gear | 40 KPH (25 MPH) = 1,250 RPM

    3rd gear | 70 KPH (43 MPH) = 1,250 RPM

    3rd gear | 80 KPH (50 MPH) = 1,750 RPM

    4th gear | 80 KPH (50 MPH) = 1,250 RPM

    All of these felt / sounded like the car was over 2,000 RPM... but maybe this car drives differently... but I don't recall that from my first few drives last week.

    01 - I presume these readings would suggest something is up?

    02 - Any idea what this could be, or where to start?

    Thanks in advance for your help.
     

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  2. rpissm

    rpissm Formula 3

    Aug 11, 2013
    1,562
    Salt Lake City, UT
    Full Name:
    Joe
    #2 rpissm, Sep 7, 2020
    Sticky tach. Mine has the same problem. Look for the thread where I talk about my issue, there are helpful suggestions in there.

    Sent from my Moto Z2 Play using Tapatalk
     
  3. awatkins

    awatkins Formula Junior

    Apr 10, 2005
    294
    SFO Peninsula
    Full Name:
    Alan Watkins
    #3 awatkins, Sep 7, 2020
    Last edited: Sep 7, 2020
    This pages lists the mph/1000 rpm from a road test.

    https://forums.vwvortex.com/showthread.php?4359921

    Easiest place to start is check your speedometer against the speed shown by a gps or by a speedometer app on your phone. With that known check the tach using the road test figures .
     
  4. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,901
    Texas
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Sep 7, 2020
    Those are all way, way too low RPMs for those speeds. See Section 1 of your OM -- there should be a table of "SPEEDS AT 1000 RPM" for each gear.

    Unfortunately, the tachometers of that era for TR and 328 have a history of electrical problems. Some timing lights also have an RPM function to use as a check, or, if you measure the frequency (Hz) of the RPM flywheel sensor signal, and knowing the ring gear has 146 teeth, you can calculate crankshaft RPM from that.
     
  5. oo7ml

    oo7ml Karting

    Dec 4, 2018
    72
    Dublin, Ireland
    Full Name:
    Mark
    #5 oo7ml, Sep 11, 2020
    Thanks for all of the feedback guys.

    Unfortunately a lot of the above has gone way over my head :)

    I'll bring it to my mechanic who has experience with these cars, and I'll go through the above points, thank you.
     

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  6. Shark01

    Shark01 F1 Rookie

    Jun 25, 2005
    3,918
    #6 Shark01, Sep 11, 2020
    I own a 90s V12 and yes those values are way low....for example, my car idles at 1,100 rpm
     

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