<all> home dyno kit??

[Roger Heflin]

On Wed, 27 Jan 1999, Mike Pitts wrote:

> 
> Seems like if you had a fast (8192 baud) home brew scan tool, 
> you could measure RPM and MPH and make the same calculations, 
> probably a bit more precisely since you would have MPH as an 
> input rather than a calculation.
> 
> Anyone know the math for this off-hand?  Might as well add it 
> to my cutom scan software (for 16198625 PCM's only, sorry).
> 
> Cool idea though.  Very creative with the inductive coil into 
> the microphone jack.
> 

I tried using the diacom data to get this sort of info.  I have 7
samples per second 8192 baud.  It does not work.  The rpm and mph are
too coarse.  1mph and 25 rpm don't give enough resolution to be able
hp over a short range.  To get reasonably smooth data I was having to
average over 7-10 samples (almost a second, and a pretty wide rpm
range). At 7 samples per second, the mph takes several samples to
change, so you really cannot get accurate acceleration numbers, and
this was the reason for having to average over a wide range. 

If you adjusted the computer and had some way to get more accurate mph
numbers then it would probably be workable.  But with 1 mph resolution
it won't work very well.

You might be able to setup an interpolation type equation for the mph
and get alot better guess.   I have a program (quick basic) to read a
diacom dbf file and do this sort of processing.  I will revisit doing
this, since I already have some code that may work with interpolation.

				Roger