By stopwatch and without speedo last year, we were at exactly 72 mph
cruising at 4K.  27x8.50 14.

Karl Wolz

----- Original Message -----
From: Joel Walker <jwalker@URONRAMP.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, December 15, 1999 5:31 PM
Subject: Re: RPM vs MPH

> > I will be starting a long, 3000 mile , trip on Friday in my Vanagon with
> > a broken speedometer.  I have ordered a replacement " cluster" from a
> > used auto parts recycler, we used to call them junkyards, but it may not
> > be here on time.  I have been using the tachometer as a rough estimator
> > for speed, about 3000 rpm I think equates to slow highway speed with
> > about 3400 rpm keeping me up with legal traffic, and 3800 rpm moving me
> > with the faster traffic.  Can anyone provide me with rpm vs mph data
> > from their experience?  I really don't want to drive 3000 miles at at
> > 3800+ rpm.  Sam
>
> actually, 3800 is good. 4000 is ok, but over 4000 rpm and your fuel
economy
> starts dropping. at least, as experienced and tested (by dufus little trip
> computer in my 86 and 88 buses).
>
> but the bentley gives 18 mph per 1000 rpm for at-the-wheel speeds in 4th
> gear (non-syncro, non-camper, with standard 185/70x14 tires). what i found
> was that it was closer to 16.35mph/1000rpm. so you could work out a little
> table like this:
>
> TACHOMETER  Walker's   Bentley's
> RPM                   SPEED      SPEED
> (in 4th gear)         (in MPH)   (in MPH)
>   2000*                    32.7         36.0
>   2200                     36.0         39.6
>   2400                     39.2         43.2
>   2600                     42.5         46.8
>   2800                     45.8         50.4
>   3000                     49.1         54.0
>   3200                     52.3         57.6
>   3400                     55.6         61.2
>   3600                     58.9         64.8
>   3800                     62.1         68.4
>   4000                     65.4         72.0
>   4200                     68.7         75.6
>   4400                     71.9         79.2
>   4600                     75.2         82.8
>   4800                     78.5         86.4
>   5000**                 81.8         90.0
>
> * i wouldn't recommend going below 2000 rpm in any gear.
> ** you'd better have Big Brass Ones to be going this speed! and damned
good
> tires, too!
>
> my speed is calculated at the 16.35/1000 and bentley's at the 18/1000.
>
> good luck! hope it helps. remember that for the 2.1 liter engines. the Max
> Torque rpm is about 3400 rpm. so if you stay above that, you'll have less
> trouble making it up the hills. :)
>
> joel