[elhigh]

Stovie,

890psi in an engine cylinder is pretty poor. Gas engines generate more pressure than that, diesels generate a lot more. Unless you're looking at a pretty long throw on the crank, that isn't a torquier engine than an ICE. Its big advantage is that, since it doesn't have to actually be turning to provide thrust, you can simply open the throttle and wait for the push's effect to accumulate into useful velocity.

In that regard it's a lot more like a steam engine than anything.

Some low-grade math! Given:

1-liter engine displacement. Assume two-stroke, single expanding.
3500 ft^3 storage volume = 98,000 liters of air.
Assume you get to use all of that volume at full power.

The engine can deliver its maximum output, drawing from that volume, for 49 minutes. That's actually not that bad when you think about it. The car probably won't need anything like its full power to cruise at speed.

Then physics steps in. You don't get the full power, you can't have the full volume. As the tank cools off the pressure falls off even more rapidly.

Frankly I'm not sure this belongs in the unicorn corral at this juncture. MDI keeps building prototypes that obviously work. The big sticking point is funding and market uptake.

Some of the details surrounding the AirPod, and a couple of ideas you suggested, however, are serious Unicorn Chow. The claim of a 5-minute refill is quite fanciful. A powerful compressor working to stuff 3400psi into an 80 ft^3 tank - 1/40 the volume you quoted - needs about 25 minutes. To do the job with the big tank you quoted would require a MIGHTY compressor, or else a lot more time.

I watched the Shark Tank teaser vid. One of the presenters mentioned using any gas station's air hose - big, big mistake. That's a fast way to lose credibility.