G-TECH

[skoty]

You may have seen them awhile back, but you could buy this small electronic unit for your car that could measure 1/4 mile times, g-forces etc. I think the unit only cost roughly $100 or so. A mate wants to know where you can buy them from?

[sergei]

They are not worth it, very innacurate.
In fact I have pulled one apart and it consist of 1 PIC and 1 ADXL103 chip (accelerometer, 1 axis).
Oh and they are very pain in the ass to use - you have to tilt the unit to set it, but I has to be set in the right position afterwards. Which makes readjustments pain in the ass, also it does not remember settings so every power off you wil have to reset it. Infact I pulled one apart to add proper buttons (which I figured how) but I decided to bin it and later built my own one with 3 axis and couple of gyros + speed sensor input for correction. Also will have datalogging capabilites. But it is a long term project.
The principle of work is pretty simple. First it gets acceleration reading, then it converts it into speed by integrating (with C being 0 - when setting it at the beggining and recalculating it constatnly - which makes it very innacurate in long run) then converts speed into distance by inegrating once again. This way you can have quarter mile time, 0 to 100 time. With power here is the simple formulas:
Force=mass * acceleration
Work= Force * distance
Power = Work / time
So we have:
Power = mass * acceleration * distance / time or
Power = mass * acceleration * velocity (only 1 integration to do for unit this way).
Oh and you input gross weight of the car - which affects the whole result in big way. if you are out by 10% the whole result would be out by about ~ 17% - becuase mass is squared in power calculation)

[skoty]

They are not worth it, very innacurate.

Yeah thats what I gathered

[KinLoud]

The later models - GTech pro are much better than the early ones.
Do a google search for it - has some good demos online on their site.

If you find an email a Gtech NZ distributor - don't bother contacting him as he isn't authorised by Gtech at all to my knowledge.

Think about buying direct from the USA. Good exchange rate at the moment

Ken
Ham
021 408 863

[Lith]

GTimer seem much more consistant

[AE82 FXGT]

The later models - GTech pro are much better than the early ones.

Yeah, I've got a GTech Pro, it seems pretty accurate, it's very very close to the Masterton timing, though I don't know how accurate that is...

[Loudtoy]

GTimer seem much more consistant

Seeing as i haven't seen a g timer run a 7 something at over 200mph in your kitchen but have seen a g-tec do such a feat i will agree with that.
+ personal experience with them also proves that