max RPMs and the Amphi

Discussion in 'General Amphicar Discussion' started by tommyintpa@aol.com, Dec 19, 2000.

  1. tommyintpa@aol.com
    Online

    <font FACE="arial,helvetica"><font SIZE="3" FAMILY="SERIF" FACE="Calisto MT" LANG="0">When I drive my waterbugs on the road I just can't make myself drive the cars
    flat out, wound up, peddle to the metal for an extended length of time. But
    in the water I find that I am standing hard down on the pedal. Without a tach
    I have no idea of how tight I've got the car wound up. They don't sound like
    here screaming like they do on the road. Will someone out there with a tach
    please tell me how many rpm's an average stock Amphi will be turning flat out
    on level ground and the same car in smooth water flat out. Thanks in advance

    Tommy in Tampa Red - 67 & White 64</font>
     
  2. David Chapman
    Online

    Flat out in the water is 3300 RPM (You have to sit in the back or water
    comes over the hood and slows you down before max revs are reached) On the
    road you get power up to about 5200 RPM (somewhere over 70mph depending on
    your tire size) at that speed the limiting factor is valve bounce - the
    inlet valve springs don't have enough time to shut and take the next gulp of
    air so the engine is strangled. The engine can be tuned with Spitfire parts
    so it can reach 6000 RPM (or even more) but you need a different cam that
    then doesn't run as well at low revs (Explains the trend in modern cars to
    variable valve timing).

    At least one manufacturer in the 1960s produced an aftermarket rev counter
    (probably for a VW) that is the same size and fits the same way as the Amphi
    clock, it has a similar layout to Amphi speedo so doesn't look odd and is
    much more usefull !

    One other recently discovered fact, the cars with the lip at the bottom of
    the bodywork (normally but not always post 1966) are lighter than the
    earlier cars, this is because the panels with the lip are made of slightly
    thinner steel, this means that with everything else equal (unlikely) the
    later cars will be slightly quicker on land and water.


    David Chapman in the UK



    > here screaming like they do on the road. Will someone out there with a
    tach
    > please tell me how many rpm's an average stock Amphi will be turning flat
    out
     
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