Re: Speedometer lying at high speeds?

[ti@amb.org (Ti Kan)]

Alexander van Gerbig writes:
> speed auto hit the end of it's range 6,200 rpm then the Motronic ECU said no
> more.  The speedo read 130 mph which amazed me, I had never gone that speed
> before.  I stayed at that speed for a very short time but I know that is
> what the speedo read.  He claims that isn't possible in his book of Audi
> specifications.  He claims top speed for a 3 speed auto 2.0L 80 in Germany
> is 192km/h, my top speed of 130 mph is roughly 208km/h.

The 1988 Audi 80/89 US brochure says that the 80 2.0L auto's top speed is
119mph, so your friend's statement is just about right on.  I'd say
that your speedo is a bit optimistic.  I wouldn't say that ALL Audi
speedos are intentionally made to read high, though.  Their accuracy
depends greatly on the rolling circumference of the tires, and that
varies from brand to brand even if the tire size spec is the same.
The degree of tire wear also influences the circumference (more than
you might think).  Add different-sized aftermarket wheels and tires and
there's even more variation.

Recently the local authorities placed a radar speed monitor/display
at a highway near where I live (it contains a large digital readout
of your car's speed as you approach it), and my A4q's speedometer is
just about spot-on.

>     He sounded angry that my car did 130 with a 3 speed auto and his 1.8T
> K04 equipped 80 tops out at 165 mph.  He had his RS2 cluster checked at a
> Bosch facility and at 150km/h on the dial the actual speed was 142km/h.

I don't think your friend needs to feel threatened by your 80, whether
it went 119 or 130.  If his top speed really is 165mph, that's seriously
fast.  Going from the 110-120mph range to 165mph requires a HUGE increase
of power, because aerodynamic drag is significant at those speeds.  The
type 89 body cars, even with its good aerodynamics, will probably need
something like 300hp to reach 165.

-Ti
96 A4 2.8 quattro
84 5000S 2.1 turbo
80 4000 2.0
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti@amb.org
 //////  http://metalab.unc.edu/tkan/
///