Paul,
You calculated that you need 0.15m^3 of air at 5psi every second. Lets assume you have an intake system that actually has two 0.15m^3 tanks with a valve that seals either one tank or the other from the intake, and that the system switches between them every second. So the first second, your compressor fills tank A to 5psi, then the compressor switches to tank B and fills that to 5psi. While the compressor was filling tank B, the engine took the air out of the tank A, then while the compressor is filling tank A, the engine takes the air out of tank B, which was just filled to 5psi. The cycle constantly repeats like this, as long as the engine is running. Sounds like a great system. Except that the engine will only be fed air at 5psi from tank A the instant that the valve on tank A opens. After the valve opens, the pressure gradually decreases as the air leaves the tank. So you may have 5psi of boost at the start of each second, at the 0.5 second mark you'll be at 2.5psi of boost, at the end of each second you are NA.
This is why, as Rara stated, your calculations for power are much lower than they should be. You were calculating how much power is required to pressurise 0.15m^3 of air to 5psi every second, not how much power is required to keep a flow of air of 0.15m^3/sec at 5psi.
Hopefully this makes sense,
Bob
