Re: RPM's vs. Speed List -Reply

From: Andy Callahan (quasideedle@uky.campus.mci.net)
Date: Mon May 05 1997 - 13:06:52 EDT


John's list also sparked some curiousity with me. I was just wondering
exactly how people measured their RPMs. My tach only has 8 tick marks for
every 1000 RPM. That means that each mark represents 125 RPM. I think
maybe some people read their tach readings wrong (i.e. when the needle was
at the first mark past 2000, they may have read it as 2100 when it is really
2125). I know this is just a minor thing, but I was just curious about the
accuracy of the readings.
By the way, here are my numbers:
        Engine: V8
        Tran.: Manual
        Axle Ratio: 3.55
        4 x 2
        Tires: 235/70/15
        RPM@70: 2250 (right on second tick mark past 2000)

At 10:36 AM 5/5/97 -0600, you wrote:
>This started me wondering what mine was doing. It's a V6 4x4 with the
>stock P235/75R15 Goodyears, and the tag on the differential says 3.9. I
>looked yesterday when I was on I-15 from Orem going to Salt Lake and
>when I'm indicating 70 MPH the tach is sitting right on 2600 RPM. This is in
>5th gear.
>
>This is a lot higher RPM reading than I would have expected from
>looking at John's chart. This makes me wonder whether my speedometer
>or tachometer is out of whack. The odometer is pretty accurate, and as I
>understand it that implies that the speedo is as well. Or maybe the previous
>owner changed the gear ratio on me.
>
>Interesting. I'll have to grab the stopwatch and see if one mile actually
>takes 60 seconds at 60 MPH indicated.
>
>>>> "L. J. Morris" <ljohn@alltel.net> 05/02/97 07:13am >>>
>Hey folks;
>
>There has been twelve members that responded to the request for your
>truck
>specs and your rpm @ 70mph.
>
>Two of you did not post your rpm's and one did not provide tire size.
>
>I am going to post this list once, thereafter if you want a copy or update
>I will e-mail it directly to you, by request. It is a *.txt file on MS
>Notepad.
>
>It may help with determining what tire size you want to install on your
>particular truck to achieve an operating rpm range. Comments welcome
>
>===================='97 Dakota SLT+=====================
>
> L. John Morris<ljohn@alltel.net>
> !!!!! ... your local *HEMI* owner ...!!!!!
> White/Driftwood/CC/4x4/5.2L/5spd/3.92SG/FIPK clone
>
>==================== Reply Separator ====================
>
>
==========================================
               Andy Callahan
      quasideedle@uky.campus.mci.net
  '97, V8, CC, Sport, 3.55, 5-speed, 4x2
          Tire & Handling Package
           All the little goodies
==========================================

 



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