Originally Posted by PhilB
That's probably going to depend a lot on how much pressure is in the tank. Like an electric, it'll have max torque right from zero, and be pretty exciting that way. But much like your old CO2 pellet gun, it'll get weaker each pass and fizzle out.
Not necessarily. If it is set up to feed air to the motor via a two-stage system, then there would be a first stage valve that reduces the pressure from the tank to the feeder line to a maximum value, then a second stage valve that reduces the pressure again to the feed into the engine.
Assuming for the sake of argument that the engine runs with a 10:1 compression ratio, then at sea level, the second stage regulator valve would need to deliver about 140 PSI to the engine. Until the tank pressure dropped to below 140 PSI, the feed would be at a constant pressure, due to the regulator valves stepping down the pressure, much like an electrical transformer.
Edit: now that I think about it, because this engine is not using IC to generate pressure, the sea level thing does not apply. You would merely need to regulate the air pressure down to whatever the engine is designed to handle.