Okay, back to the original topic.

Let’s try it again for a 3 litre engine at 6000rpm with 15 psig. Instead of a turbo, say our compressor is a very long cylinder and piston with a cross sectional area of 1/15 square inch. That means this piston needs 1 pound force against 15 psi. The engine will consume 9000 litres per minute of air, but at double normal density. 9,000,000,000 cubic mm. The piston in our long compressor cylinder has a surface area of 1/15 sq inch or 43 sq mm so to displace 9G cubic mm per minute it would move at 9G/43 = 209,302,325 mm per minute or 686,687 feet per minute, against 1 pound force, so 686,687 foot pounds per minute. 686,687/33,000 = 20.8hp = 15.52kW. That’s pretty simplistic, but it’s a starting point.