Why did Stan Meyer's water car need a metal bellows? Thin mountain air

In 1990 an interviewer put it to Stan Meyer: up in the mountains a water car doesn't use outside air, so thin air shouldn't matter. Stan walked him over to the buggy: "metal bellows, which now allows to control the amount of ambient air going into the engine of the car," with sensors for the air pressure, "the same as a conventional car." Why would it care? Stan didn't burn pure hydrogen and oxygen; he mixed in outside air and recycled exhaust to slow the flame to gasoline's pace, and that air thins with height. In the standard atmosphere, a breath of air in Denver holds about 85% of what it holds at sea level, and on top of Pikes Peak about 65%. A sealed metal bellows is also how a barometer works: it swells as the outside pressure falls, and carburetors of the era used one to correct the mix at altitude. Today a pressure sensor does that job in every car. The full 1990 interview is on stanslegacy.com.

About the voices. The narrator is NeuralStan, an AI voice the archive uses for its made films. Where you hear Stan Meyer, it is Stan: every word of his is cut from an original recording, and nothing he says was synthesised.

Sources

• Stan Meyer at his garage · 1990 interview
• Stan Meyer, 1990 interview at his garage, at 35:45 and 36:42 ("The metal bellows") — transcript on stanslegacy.com
• Same interview, at 29:09 and 32:38: ambient air through the gas processor, and exhaust gases cycled back in to modulate the hydrogen burn rate
• International Standard Atmosphere: air density 1.225 kg/m³ at sea level, about 1.047 at 1,609 m (Denver, 85%) and about 0.79 at 4,302 m (Pikes Peak, 65%)
• Aneroid capsules and bellows: sealed, partly evacuated metal cells that expand as ambient pressure falls; used in barometers, altimeters and altitude-compensating carburetors