On Tuesday 12 July 2005 08:50 pm, R. I. Nelson scribbled:
> Chetan Bhargava wrote:
> >http://www.surpluscomputers.com/store/main.aspx?p=ItemDetail&item=CES10539
>
> How can this unit tell the following
> Your speed
> what distance you have traveled
> your  vehicles H.P.
> Does it have a GPS unit in it?


I had one of these some years ago (and should still have it somewhere).  
Before launch, you level the device, and hit the reset button.  As soon as it 
detects acceleration, it starts measuring/counting/timing.  Based on 
acceleration and time, it can calculate distance, speed, 1/4-mile time, etc.  
HP is a back-calculation from the acceleration/time and the weight (which you 
enter).  It cannot account for drivetrain losses, so it gives you rear-wheel 
HP, as any dyno would measure, which is different from published (flywheel) 
HP figures.

At that time, I remember some magazines testing it and found it to be within 
0.2-0.3 secs for the 1/4-mile calcs, but less accurate f/HP calcs.  Some 
magazines even claimed that it would be more accurate than a 1/4-mile track 
timer, since those measure the end speed based on the difference in time 
between 2 sensors spaced some yards apart, and vehicle speed is still 
changing during that short time.

Not bad for a device that cost ~$100 (at that time).  It was awesome for 
determining hp changes when tweaking/tuning, and the only thing I wish it had 
was a temp/humidity detector to adjust each measurement to a common 
reference.

Cheers,
-Neil.



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