RE: NITROMETHANE SUBSTITUTE.
call the local dragstrip and see if they sell racing fuel. a good one will sell or tell you where to buy nitromethane. its what thy run in funnycars, those v8 that do the 1/4 mile in 6 seconds.
nitromethane is simular to nitrous oxide, except nitrhmethane also has a fuel in it, so it will burn on its own. the stoicometric ratio is 1.7:1. gasoline is 14.7:1 and ethanol is some where about 6:1 (i think)
the other reason it is used (in the small stuff atleast) is the cooling effect the freed nitrogen has on the cylinder. its basically a liquid turbocharger, enables you to burn more fuel than the O2 from the air would otherwise let you.
but last i check a few weeks ago, a race shop in phoenix az was selling nitromethane for 20$ a gallon. if you buy ti online its triple that, cuz of hazmat. (40$)
its not that hard to get. just exspensive.
try the FAI mix. you might like it.