At 6 gallons per ton of wood, not a very productive process.
Sorry about the units, but they're the numbers I found a few weeks ago when a friend was talking about needing methanol as part of the process for making proper biodiesel from vegetable oil...
The wood is burnt in a fire with a restricted grate. The result is that the gas drawn to the engine contains a high proportion of carbon monoxide. The engine performance seriously sucks. :-)
Just need something that you can unbolt the LPG mixer and bolt on the methanol carby and CO mixer... :-)
After all, nobody in their right mind would be running a vehicle on petrol! :-p