If you don't mind giving up the mapping capability you can even get one in
the form of a speedometer gauge. Of course Lord Lucas would then know about
it once you installed it in your dash :-)
Larry Miller
----- Original Message -----
From "Mark Endicott" <endicott at nashville.com>
To: <spridgets@autox.team.net>
Sent: Tuesday, June 13, 2000 10:36 AM
Subject: Re: calculated speed
> You guys are doing this the hard way! Just put a GPS in the car and
drive,
> it will tell you how fast, how far, average speed, and where you have
been.
> Now that the "SA" is turned off accuracy will be +/- a couple of percent
no
> matter what size tires you have. Mine has a detailed map on it so I won't
> get lost, plus it sends my position back home and to the Internet. A few
AA
> batteries will run it for a long time and Lord Lucas won't even know it's
> there.
>
> Mark
> 70 Midget
> Nashville
>
>
>
>
> > Here's How I calculated my speed.
> >
> > 1) check the tire circumference using my wife's sewing tape measure,
> calculate
> > how many rotations would be required per mile.
> > >fourth. Divide by the number of inches in a mile(63360) and you should
> get
> > >miles per hour.
> > >
> > >{(rpm/rear end ratio)x 60 x C }/ 63360
> > >
> > >So for a 4.2 rear end, 69.625 inches per turn of tire, fourth gear:
> > >(6000/4.2) x 60 x 69.625 / 63360 = 94.18 mph, at 5k rpm = 78.49mph
> > >
> > >
> > >I'm sure someone with a better memory of math will correct me, but
> luckily I
> > >play with DNA for a living and don't do gobs of math.
> > >
> > >
> > >
> > >> I havn't seen anybody talk about tire size which can have a very
> > difinite
> > >>effect on speedo error and correct top speed. Look at any tire chart
> and
> > >>you will see a big difference in tire circumference with the tires
sizes
> > >>very close together if not the same size. Don't forget to take this
> into
> > >>consideration. Does anyone one out there have the formula for
> determining
> > >>top speed using tire circumference, axel ratios, and rpm's?
> > >>
> > >>
> > >>BOB
> > >>65 Midget vintage racer
> >
>>________________________________________________________________________
> > >>
> > >>
> > >Regards,
> > >Glen Byrns
> > >'59 Bugeye
> > >
> >
> >
>
>
|