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BBLM lightweight flywheel

Discussion in 'Boxers/TR/M' started by msgsobe, Nov 26, 2007.

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  2. 2NA

    2NA F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 29, 2006
    17,740
    Twin Cities
    Full Name:
    Tim Keseluk
    I'm not sure you have the whole thing there. Probably should be some steel wear plates.

    You likely would also need the clutch that goes with it.

    The biggest advantage would be rocket-like acceleration because of lower rotating mass.

    The bad news is that it would be more difficult to get the car rolling from a dead stop and like applying the brakes when you took your foot off of the gas.

    A pretty jerky ride.

    I don't see a ring gear for the starter. It might be hard to get the car started.


    Not recommended for street driving.
     
  3. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,858
    Tim - Your comment concerning "...rocket like acceleration..." made me think. This is a bad thing (my thinking, that is).

    I suspect that a lighter flywheel will provide little, if any, acceleration advantage. When compared to the moment of inertia of the entire transmission, wheels, and CV joints, the difference in weight of the rotating flywheel seems insignificant.

    HOWEVER, while in neutral, as during shifting, the engine will respond significantly (if not a great deal) faster. Hence, the RPM will drop faster while upshifting and, during double clutching, a blip of the throttle will raise RPM faster.

    I suspect that the advantage will be in engine response during shifting, and not acceleration. Moving from a stop will be compromised because of the lack of rotating inertia, but this could be overcome with finesse on the clutch pedal.

    Jim S.
     
  4. ferraripete

    ferraripete F1 World Champ

    correct! the first thing you notice w/ a light flywheel is the engine seems a bit more alive when reving. the next thing is that the rpms drop quickly between shifts. then the next thing is that the flywheel makes leaving from a dead stop more of a clutch slipping event ...thus expect more clutch wear.

    great for the track however!

    pcb
     
  5. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
    2,149
    way north california
    Full Name:
    chris morse
    I have had a couple of auto x P cars, just 4 cyl but the light wheel was really noticeable, the engine more responsive. My toyota 4 cyl work truck has a 12 lb billet and a few goodies and it stalls more often with the light wheel, but it really made a big difference in responsiveness.

    When the clutch went out on my 308, I had a local machinist take it down to 8 pounds, roughly half of its original weight. It takes a bit more attention, but i rarely stall it. The real secret to making clutches last is to just slip it enough to get the car rolling, Then hammer the throttle. I would absolutely do it again.

    best,
    chris
     
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  7. 2NA

    2NA F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 29, 2006
    17,740
    Twin Cities
    Full Name:
    Tim Keseluk
    I wondered if I would have to clarify. I was referring to the "feel" of the car, not 1/4 mile E.T.'s.

    It won't actually make the car faster overall but you will definitely notice the surge when you start out with a light flywheel.

    Overall in a street driven car you would hate it.
     

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