I know I'm way behind on this ongoing motorcycle computer/ arduino thread. I read a few of the posts, made remark or two at the beginning. Been working on a similar, less complicated project.
I used sirmorris's method to store data on an sd card:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235125412
It's an arduino set up. I use it on a Harley sportster to count and store pulses from the speed sensor. With the count(pulses/second) stored on the sd card, the card can be removed from the arduino cktry., then plugged into my computer.
The data can then be loaded onto a spreadsheet, such as excel, then the data can be used to calculate things that happened over a period of time, speed, acceleration, rpm, make curves on the spreadsheet, calculate derivatives or integrals from the various curves.
I haven't been able to calculate torque or hp yet, but I can graph speed and acceleration curves. If I make any mechanical changes to the bike, those curves will give an indication of any changes in performance that might have resulted from my mech. changes.
From the speed sensor pulses, I can calculate wheel rpm, mph. Using drive train ratio info from my bike manual, I can calculate engine rpm. I could also collect data from the cam position sensor, which feeds an input to the ignition and possibly get a direct engine rpm read from that. My arduino set up would work with that also.
I tried other methods to read and count pulses from the ignition output, but the pulses are very, very messy due to the connection to the ignition coil. However, that is the same point where an electronic tach reads from.
An electronic tach uses an LM2917 frequency to voltage converter. Output from the LM2917 is a varying dc, which varies in proportion to pulse frequency, the tach merely reads it in the same manner as a voltmeter. However, to store that data, 2917 output would need to be converted to digital. An arduino could do that, then use sirmorris method to store digital on an sd card, WHEW.
That's my $.02
Any body have any ideas of how to use rpm, speed, and time to calculate torque and horsepower?
I've been using different formulas, calculus, curve analysis, but I'm doing something wrong :o
PO'T 