Clarkey,
I've recently bought an alternative to a Stack system. It's a datalogger from a kart called the MyChron Pro. it comprises an LCD display that shows revs, speed and two temperatures, five sequential shift lights and two over temp lights. It logs for 62 minutes (you can extend this if you lower the sampling rate), records lap-times (beacon supplied) and calculate track maps (sprints and circuits).
The unit is not as sexy looking as a Pi or Stack, however, it's a quarter of the price (£500). The software is excellent, allowing you to calculate all the usual beardage things (linear g, gears, wheelspin, horsepower etc.), the only limitation is the inputs (speed, rpm, two temps, lateral g, ie. no throttle/steering position sensor).
I'm currently constructing a web-page about it but if you would like more info feel free to email me, I can put you in contact with the importers and send you samples of the data I gathered at Donnington on Monday.
Cheers,
Graeme.
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graeme finlayson / tyre warmer / fluke motorsport
graeme.finlayson@vicorp.com / www.fluke-motorsport.co.uk