[Wolf1]

14.7 psi of boost at sea level.

At 5000' in Denver, Colorado, this "boost" would be only 12.2 psi, as the atmospheres height at 5000' is only 99 miles high vs 100 miles at sea level.

A non supercharged engine will perform better at sea level where it has more boost (14.7 vs 12.2).

Without this atmospheric weight or "boost," the engine would not run.

Why? Because an engine creates a vacuum as it rotates thereby allowing the higher pressure atmosphere to rush in and fill the vacuum with 14.7 psi of boost.

Note: This boost does not show up on a typical 0-20 psi / 0-30"
Hg gauge as 14.7 but instead as "0" on the 0-30" Hg scale.

Now imagine on an ascending scale that the 30" Hg is 0 psi and the 0" Hg is 14.7 psi and you have an "absolute" pressure gauge.

Add the 20 psi to the 14.7 psi and the gauge markings would be 0-34.7. Floor the throttle at sea level and the gauge will read 14.7 psi and 12.2 psi at 5000' in Denver (with "0" inlet restriction).

With a supercharger and 6 psi boost, your new absolute pressure gauge will read 20.7 (14.7+6=20.7) at seal level and 18.2 (20.7-2.5=18.2) in Denver.

Here's how you determine if your engine is utilizing all of "natural boost."

If the gauge reads 4" of vacuum at wide open throttle, your engine is losing 13.6% of it's power or 2 psi of "natural boost." This is a simple equation that few really understand. 2 psi lost÷14.7=13.6% HP loss.

To eliminate the pressure losses, install larger non restrictive inlet components (filter, MAF meter, throttle body and/or inlet manifold). The
2 psi loss with a 6 psi kit (18.7 psi absolute) is 2÷18.7=10.7% HP loss.

This is a big number as 10.7% of the supercharged HP is 32 whopping HP on a 300HP engine. Whether fuel injected or carbureted, ALWAYS try for a "0" reading.

Now lets see... how do I remove the effects of pressure loss... well in an NA I could use simple sources of boost or pressure to equalize the loss, in other words, either you improve what you got or you supplement it.

Now we are not talking about runner length and plenum design for your intake, that is a long subject to cover, but basically the runners and plenum effect your power curve, meaning your engine can run out of air at higher RPMs or breath fine at those levels, but suffer at lower rpms. Torque, HP, Power band...