I took an old gas lawn mower- removed the muffler and attached a pipe with a long rubber hose attached to the pipe. I put the hose in the tunnel and seal it up with dirt.
I run 2 cycle gas and get as much oil in my mixture as I can without fouling the plug. Smokes the crap out of the tunnel and I can let it run for hours.
someone once told me to take a tank of propane - fill the tunnels with propane and light it - Don't want to blow up the neighborhood but sure sounded like a something I would have done when I was 13!!
