I made an .otx with your last version. You also have the V8 and V4 the sound sample. You can change to these in the script
https://drive.google.com/file/d/0B96RrTcNJsI2dmQwZGIyNVBwWGc/edit?usp=sharingThe script is pretty messy as i didnt cleaned up the dash stuff that can only be used on Hrrhrr sound test vehicle.
the most important to play with to get the right force and right sound pitch, is with these lines
const gears = [ 16.124, 8.641, 4.58, 2.00, 0.82, 0,40, -5.224];
const ratio = 1.0;