GT Motorsports: 370Z Supercharger system development

KEVTEX

The quantity of air that flows through the engine at a given boost pressure, temperature and rpm is detemined by the flow characteristics of the engine(port size, valve size, cam, displacement) and not by the characteristics of the compressor that creates the boost. Other than minor differences in parasitic losses from bearings and belts, boost is boost regardless of how the engine created it.
Silo's chart indicated a larger turbo could flow more air than a small turbo at a given pressure, which is not true if they were both used on identical engines. It would be true if the larger turbo was used on a larger engine.

BalanBro

Bingo! There you go, this guy speaks the truth. The boost pressure you are seeing is measured at the intake manifold. It doesn't matter if it got their through a turbo or supercharger, nor if it was through 10" piping or a 1" garden hose. Two completely different FI setup's with equal manifold pressure and temperature (assming they are both effectively intercooled) will yield the same engine output. If it didn't, it would violate the laws of thermodynamics.

What happens most often in the case of a turbo that is too small for its application is that it reaches a point that it can't maintain sufficient cfm for a given engine rpm, and the measured manifold boost pressure will drop accordingly. I know several folks have experienced this with small gt25's on their sr20det's.