Air Date: October 18, 2006
A compressed air cylinder can blast itself through a concrete wall.
Once the MythBusters constructed a launch tube and perfected shearing off the cylinder’s valve, the cylinder shot entirely through their constructed cinder block wall and damaged the solid concrete wall behind it. The MythBusters were also aware of recorded instances of such a thing happening.
A compressed air cylinder can power a speedboat.
The two cylinders could only propel the boat 120 feet at a maximum of 5 knots. A second attempt resulted in the boat barely making half the distance, and barely registering any speed at all. It was jokingly said that Jamie could swim faster than the boat and that the speed should be measured in "miles per day" rather than miles per hour.
An engine can run on gunpowder alone.
Even though gunpowder has a greater energy density than gasoline, none of the three historical designs worked for more than one cycle; the team could not find a practical or reliable way to feed the gunpowder into the engines (Most likely because black powder is not a liquid and therefore is not transported as easily). They were also unable to convert a modern lawnmower engine to run on gunpowder.