[QUOTE=spdrun;3107467]I suspect that they used one or two cylinders of the truck's motor as a compressor. Basically you can get a fitting that replaces the spark plug and uses the engine's compression to pump air. This being said, I'm not sure if the 150 or so PSI generated by an engine's compression ratio is enough to power a long-distance air cannon.[/QUOTE]

If the Air Tank is big enough the "goods" can be under pressure (even if it is decreaseing pressure) right to the point where they exit the Barrel/Pipe.

JC Whitney & company used to sell an Air Hose that screwed into the Engine by way of a Spark Plug Hole for emergency Tire inflation. But, I think they ment you just cranked the Engine and not starting it.

__________________
84 300D, 82 Volvo 244Gl Diesel