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[Stopwatch image] EZ Rally Timing
by Gary Starr



Looking for a stock odo timekeeping technique that has the accuracy of a computer yet is so easy anyone can do it with just a clock and 4-function calculator? Try this proven one:

EZ Rally Timing Method

Step 1

At the odo check, compute and record the corrected minutes per 0.1 mile factors for all the casts of the entire rally in the following format:
      +--------------------------------------------+
      |  TT.TTTT0DDD    (for 10 digit calculator)  |
      |      or                                    |
      |  TT.TTTDDD      (for 8 digit calculator)   |
      +--------------------------------------------+
   
where TT.TTT(T) is the corrected min/0.1mi and DDD = 001 (DDD is distance in 10's, 1's, 0.1's miles).

Example:

      +-------------------------------------------------------------+
      |  CF (correction factor) = your net mileage @ odo check /    |
      |                           official net mileage @ odo check  |
      +-------------------------------------------------------------+

                                = 10.25 / 9.85 = 1.040609137
   
Cast = 40

(Since corrected min/mi = 60 / (cast * CF), then)

      +------------------------------------------+
      |  CORRECTED MIN/0.1 MI = 6 / (CAST * CF)  |
      +------------------------------------------+

                              = 6 / (40 * 1.040609137) = 0.1441xxxxx
   
Record for cast 40:
         0.14410001    (for 10 digit calculator - truncate to 4 decimal
                        places, add 3 zeros and a one)
            or

         0.144001      (for 8 digit calculator - truncate to 3 decimal
                        places, add 2 zeros and a one)
   

Step 2

Enter into memory the factor for the first cast.

Step 3

Now clear the display (but not memory) and enter your out time in the same format where TT.TT is your out time and DDD is your odo reading at the outmarker (or place where TT.TT is your out time).

Example:

      out time = 21.00, odo = 36.4:

      Enter into display:

          21.00000364   (for 10 digit calculator - out time in minutes,
                                                   decimal, 5 zeros, odo)
              or

          21.000364     (for 8 digit calculator  - out time in minutes,
                                                   decimal, 3 zeros, odo)
   

Step 4

   +--------------------------------------+
   |  Now press +, MR (memory recall), =  |
   +--------------------------------------+
   
And presto - you have the TOD clock time TT.TT (eg. 21.14 min) for the odo mileage DD.D (eg. 36.5 mi)!!!
      (display reads 21.14410365 for 10 digit calculator
                          or
                     21.144365 for 8 digit calculator)
   

Step 5

Keep pressing = to match DD.D to your odo, and wah-la, you can give hacks every 0.1 mile if you wish (like when approaching a control - eg. 21.28 min @ 36.6 mi, 21.43 min @ 36.7 mi, etc.) with accuracy that will rival a computer. You can easily get 2's or less with a steady driver (Dave Fuss and I got 8 points in 10 controls using this system with just a checkpoint TOD clock and stock odo!).
                     OR
   
Just press = enough times to match any odo reading at which you want the time.

Notes

When the time exceeds 60 (the hour), just subtract 60. Then press +, MR, = to continue for the next 0.1 mi.

At speed changes, press = until the mileage matches your odo, record the result (entire display), enter the new factor into memory for the new speed, and go back to step 3 using the recorded figure as your out time to enter in the display.

Pauses/gains are done normally (+ pause =, - gain =) followed by +, MR, = to continue for the next 0.1 mi.

Equipment needed

  1. 0.1 mi reading odo (don't need or will use reset).
  2. 0.01 minute TOD (time-of-day) clock (checkpoint clock is fine). The above clocks are available through the manufacturer or:
  3. 4-function calculator with 1 memory (to be class S "unequipped" legal): Other desirable but not absolutely essential calculator features: Calculator recommendations: Beware: Most calculators (except those above) loose their memory after auto power off.
(rev 4 - 03/07/96)
[Mail] Email comments/questions to Gary Starr