This will take some experimenting. I might start with removing the injector and glow plug for 1 cyl and see how much air pressure it generates at every other stroke.
I can tell you that without looking. Figure 20:1 compression, you should be getting in excess of 300 psi. I think you are mistaking volume for pressure.
A 240 engine would have 0.6l displacement per cylinder. Valved for the purpose you'd get 0.6l per revolution, so at 2400 RPM you'd get 1400l/m per cylinder, or about 50 CFM. -- Jim
