More: HP / Torque calcs

[Ward]

Most of the system output rpm to a resolution or 25 RPM/bit.
Vss is 1 MPH/bit
Ward

On Mon, 16 Aug 1999 13:07:43 -0500 (CDT), Roger Heflin wrote:

> 
> 
> On Mon, 16 Aug 1999, Dave Zug wrote:
> 
> > Well I have thie little graphing thingy putting lines on the screen, 
> > easy enough.  It reads the scan software's datafile directly 
> > too. 
> > 
> > 2 things to note: even at 8192 baud the number of samples per second 
> > makes the graph pretty chunky. Also my RPM data seems to be wierd.. I 
> > mean the readings can go like this (this is WOT in 2nd grar):
> > 
> > this is not actual data, but a representation
> > 
> > 2600
> > 2750
> > 2700
> > 2775
> > 2875
> > 2925
> > 3150
> > 3150
> > 3325
> > 3425
> > 3600
> > 3575
> > 3700
> > 3825
> > 
> > 
> > see it's like there was hard knocking and severe spark reduction but 
> > there actually was none at all! my delta rpm graph is a 
> > sawtooth! Might it be stale old values being pumped out by the ALDL 
> > when its too busy to update them or something??? am I correct in 
> > asuming the time intervals are EXACTLY equal between the readings? is 
> > the time differenntial a steady value for 8192 baud? my stream has 56 
> > or something bytes in it.. I can calculate the time ass-uming the 
> > packets are heel to toe with no delay. has anyone calculated this?  
> > blah blahblah.. {diarhea of the fingers deleted} ;-}
> > 
> 
> I have ran the calcs.   And I have noticed much the same you have.
> 
> I believe to get even reasonable numbers you will need to add some
> sort of interpolation, and smoothing algorithm to get reasonable
> numbers.
> 
> Mine were getting pretty good hp numbers using the data for several
> samples (the number of samples varied depending on the speed or rpm -I
> don't remember which).  I assumed then that the hp was the hp for the
> center position, but this method lacked some coverage and resolution.
> 
> The only real way I could see to do it, would be to increase the
> sampling speed by either modifing the data stream from the chip.   And
> beyond the rpm being rather flakey, only having the speed in units of
> 1 mph is rather limiting on the accuracy area too.
> 
> I did assume that the samples from the data file where equally spaced,
> I don't know if they really are, my guess would be they are probably
> fairly evenly spaced, and it really does not matter given that the mph
> number is not accurate enough to computer hp reasonably.
> 
> 			Roger
> 





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