More g-stuff

[Watson, Bill]

aec at cedar.netten.net    wrote;

>I'm working on a product that would attach a hall effect sensor
>to the right front spindle of your vehicle and read the grooves
>in the rotor.  Interpreting that information would give you
>VERY accurate 1/4 times / acceleration times / hp.

You have a good idea, but as you might guess, every system has its
advantages 
and disadvantages.  We have tried your method already and found that the
'hill' issue becomes critical again.  You will have accurate speed but
not 
accurate HP because the slope of the road will not be accounted for.
For 
good results, we had to test not only on the same road each time, but 
initiate the accel at the same SPOT in the road at the same VELOCITY
too.  
For this reason, we've gone back to the accelerometer.

Here's the summary;
Accelerometers compensate for hills but don't *know* velocity.
Velocity transducers know velocity but don't compensate for hills.

It's your choice.

This is why we (g-curve) use the accelerometer for g's only, then use
your 
speedometer for speed.  (Our weakness-- we don't have electronic 
datalogging.)

This is also why the 'OnBoard Dyno' has BOTH an accelerometer and
velocity 
transducers.  It is the most accurate for this reason, but pricey at
$1300 
plus.  Additionally, it is tougher to move from car to car.

Bill