WE hear everyone talk psi. Is not psi air that is not going through s/c that is leftover I think a lot emphasis is put on higher psi???? i don't get it when saleem and roush only run 6psi as matter of fact I beleive all s/c comes with anywhere from 5 - 8lbs psi. I read here everybody wants more psi when I think it really is not necessary. an engine can only take so much air in a intake stoke and that's it. To get more air you need different cams etc. What do ya think??

 

The beautiful thing about air is that it is compressible. On a normally aspirated engine, it is always at atmospheric pressure, and that limits the amount of oxygen that can enter the cylinder. By applying boost above atmospheric pressure (i.e., "X" psi), you can compress the air and get more oxygen molecules into the same cylinder volume. So, even though the cylinder volume is fixed, the mass of the air (and thus the number of O2 molecules) that can be put in there is not.

 

pounds per square inch

 

It's all about shoving more air into the cylinder, whether it be via supercharger, turbocharger, or nitrous. The first two compress the air and force it into the cylinder. Nitrous splits the oxygen and nitrogen. At the same time, nitrous vaporizes which cools the air. The cooler the air, the more dense it gets. Thus allowing more oxygen into the cylinder. The more oxygen you have in the cylinder, the more fuel you can put into the cylinder. If you read around the forums, one major issue that's been happening (to the ones with poweradders) is running out of fuel-not enough fuel in the cylinder compared to the amount of oxygen in the cylinder. This creates a lean condition. There needs to be a balance between the two.
Anyone that has a poweradder and is wanting more HP via more psi...needs to be thinking about fuel supply at the same time. The two go hand in hand. You can't add too much oxygen without adding fuel.