i've borrowed one for the night - anyone played with one of these things ? any advice ? :cool:

(it measures 0-60, quarter mile, g force etc - www.race-technology.com).

its just a box which plugs into nothing and doesnt use gps seemingly - anyone know how the feck it knows what speed yer doin/how far yer've gone ?! :eek:

My guess is gyroscope, but this is just a guess. The other thing might be using electronic gauges (made one last year for a uni project).

I've used one of these in the past (but not on the scooby).

They don't use GPS - GPS only gives a speed update every second which is not accurate enough for timing.

It uses an electronic device called an Accelerometer. Put simply this is a tiny slab of metal suspended on springs inside a chip (I kid you not). When you accelerate the slab moves about and the chip senses how much it has moved, and hence your acceleration.

Combine this chip with a small processor and you have a performance meter.

They are good toys. Make sure you calibrate it properly and put the right weight etc in or the results will be cobblers.

It will also be measuring the >real< speed of the vehicle. The scooby speedo will read over. My P1 speedo reads about 5mph over at 60mph so make sure you run the car to 65mph+ to get a 0-60 reading.

Have fun and be careful on the test "track".

Marc
www.impreza-p1.org.uk