electronics project: collect mph data

[kevin-design]

Since c4's have that handy digital mph readout, and since I dabble in electroincs from time to time, I was considering building a little 0-60 circuit to document performance changes and/or driver improvement. It would be really simple, just a plug in module and a reset button. Reset at wherever you're stopped- timer begins when first non-zero reading begins, stops when 60mph (or other set mph) is reached. Lather, rinse, repeat. Really very easy. The only trick is that I need an accurate way to collect the MPH data. Any tips? or is something like this already readily available? I'm sure any racing computer would happily tell you that statistic and plenty more, but I'm going for simple and easy here (oh, and cheap. did I mention cheap?). Thanks for any help!
-kevin

 

[G Winter]

Can't you just use the signal from the output on the transmission? I am not sure but I would think that would be a paulse signal. All you would have to do is read the pulses.

Glenn

 

[MBDiagMan]

Well the Vehicle Speed Sensor (VSS) signal could be used, but the problem is that it is an analog signal, just a tach/generator. That means you would have to do an analog to digital conversion.

That said, if you are only going to be measuring to 60 MPH you could use an op amp and a trimpot to set whatever voltage it is when 60MPH is reached and use that to trip your timer.

It's been thirty years or so since I did such design so I'm quite rusty. Even though I was pretty good at both Analog and Digital design, I would prefer to do this against a digital signal. It is just simpler to accomplish and eliminates the need for "tweaking."

Good luck,

 

[Aurora40]

I'm pretty sure you can get speed data through the ALDL connector. With some PC software, it would be really easy to analyze the data and compute things, provided you knew the timeframe between data points.

 

[vetteboy86]

There is a similiar device out there, and pretty cheap I might add. It does some more functions than just 0 to 60. I think I saw them for 49 bucks, some of you know them as a G-TECH meter. I believe that this device uses an accelorometer. The micro inside the device must sample acceleration over time and calculate when you have reached 60 mph.

 

[G Winter]

There is a similiar device out there, and pretty cheap I might add. It does some more functions than just 0 to 60. I think I saw them for 49 bucks, some of you know them as a G-TECH meter. I believe that this device uses an accelorometer. The micro inside the device must sample acceleration over time and calculate when you have reached 60 mph.

G Tech meter.. got one. I didn't understand that was the object of what kevin was trying to do . I bought mine on a surplus computer site for $35 last summer.Works quite well. Mine is an older model , the new models come with graphics and sell for over $200
www.gtechpro.com
Glenn

 

[vetteboy86]

I think he was trying to calculate zero to 60 times, by starting and stopping a timer circuit.

 

[G Winter]

The G tech gives you 0 to 60 times.. 1/4 mile speeds and time ,and estimated HP .
If you search , you just might find one of these old models somewhere really cheap.

Glenn

 

[vetteboy86]

I do like kevins idea though, it could probably be built for far less. I know with the parts we have at work, I could probably build something like that for under 5 bucks. I would only be out my time. Kevin if you get something going, and have any other ideas, feel free to share.

Craig