I have been looking into home brew dynos and found a few interesting sites that talk about the "home dyno" or "Streetdyno" which uses the weight of the car/bike as the load. You record the engine RPM and software to calculate the HP from the acceleration

http://www.ontrackdigital.com/dynographsandtables.html" onclick="window.open(this.href);return false;
http://members.fortunecity.com/jasoncuadra/id47.htm" onclick="window.open(this.href);return false;
StreetDyno

Wondering if anyone here has any experence with the "home dyno" or "Streetdyno"?