Re: Overhead Computer vs. Manual Mileage Calculation

From: andy levy (andy-dml@levyclan.us)
Date: Wed Aug 20 2003 - 22:08:17 EDT


Michael Quigley wrote:

> droo said:
>
>>I have a 4.7 with 3.55 gears manual trans. I'm getting 16-17 mixed driving.
>>That's with high speeds on the highway.
>
>
> I'm going to do a more scientific mileage investigation using the old
> fashioned "miles over gallons" manual calculation. Everything I've said is
> based on the calculations of the overhead "computer" in the cab.

You definitely have to.

geekmode = on
Mostly because my father always did it, I keep track of my mileage at
every fill-up. He used a little spiral notebook, now that we're in the
comptuer age we both use a spreadsheet. At every fill-up, I record 6
things:
        Date
        Odometer
        Elapsed time (from the OHC)
        Gallons
        $/gallon
        OHC mileage
 From this, I calculate:
        Projected annual mileage (running average)
        Total cost
        MPG
        Miles/day
        Gallons/day
        "Engine hours"/day
        $/day
        Miles/engine hour
        Gallons/engine hour
        $/engine hour
        $/mile
And of course it's all graphed. Like I said, I'm a terminal geek.

In the 6 months I've had this truck, the OHC has been pessimistic
(showing lower mileage than I calculate) 8 times out of 40 fill-ups.
Meaning that OHC number is normally higher than my real mileage. My
average calculated MPG is 15.88, average OHC reading is 16.2 MPG.

My readings have been fairly close. Some people have observed
differences of 1.5MPG regularly.

geekmode=off
        

-- 
-andy

http://home.twcny.rr.com/andylevy/dakota - andy-dml@levyclan.us -------------------------------------------- "Whatever Adam does, do the opposite and you'll be fine" -Bob Tom --------------------------------------------



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