Re: speedometer error

[Jay Negrin <jmnegrin@domain.elided>]

"Michael S. Sweigart" wrote:

> My GTV6 speedo never deviates- it stays consistantly at Zero (0) MPH.
> Hows that for precision? I just go with the flow of traffic and haven't
> had a ticket in years despite having no working speedo. So if we are
> comparing who spent less on worrying about speedo accuracy, I win  =)
>
> I was thinking about sticking little post-its on my tach that had the
> speed mapped out by pacing my wife's car but that thought quickly
> diminished. I think 3300 rpm is 55mph or something like that.
>
> No map, no mile markers, no gps, just common sense and a good knack for
> avoiding "the man".
>
> -Michael in New Joisey
>

Common sense?  My, oh my.  How unusual in this day and age.  :))

All kidding aside,

If you wanted to figure it out, pick a gear, or several, (just not at the
same time, please!)
Set your tach at an appropriate rpm for the road.  Numers with lots of
zeros at the end seem to make the arithmetic easier.
Measure you time over a pre-measured distance.  One mile, 1/2 mile,
whatever you need.  Do the necessary math, and voila!  You can come with a
good approximation of speed per thousand rpm.  My Alfetta is nearly, but
not quite 20 mph per 1000 rpm.

The beauty of this is that you can even figure out kph/1000 rpm, with the
proper math and arithmetic.

I new all that nav rally stuff I've been involved with had *some* use,
somewhere

Jay Negrin
ARO So Cal
76 Alfetta GT

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