One last attempt to explain from a different direction why CFM capability of the supercharger/turbo is completely irrelevant to my analysis of RIPP's claim of 40% gains at 1800 rpm. Please actually read through this and put some effort into understanding it before responding.


CFM = Cubic Feet Per Minute

That's a rate of flow of a volume of air per unit time. A volumetric flow rate. That's it. Volume/time. Pressure, mass of air, or number of molecules is completely independent of flow rate.

What is the flow rate of the Pentastar engine at 1800 rpm? For simplicity, we will ignore extra volume in the ceiling of the combustion chamber, valve overlap, etc. Let's just go by the displacement.

3.6 L total displacement, but each cylinder requires 2 rotations of the engine to intake and exhaust 1 cylinder full of air.

So (3.6 L) * (1800 rpm) / 2 = 3240 L/minute

Again... this is just volume of air. Pressure, temperature, etc., are all unspecified. It does not specify the AMOUNT of air flowing through the engine. Just the VOLUME. The AMOUNT of air depends on the volume, pressure and temperature.

So what's the volumetric flow rate of the engine at 1800 rpm with 0.3 psi boost? At 0.6 psi boost? At 37 psi boost? The answer is always 3240 L/minute. The difference is the pressure and temperature of the air, which results in a different AMOUNT of air, but the same VOLUME.

Even if there's some inefficiency with cylinder filling (intake valve isn't open long enough to equalize pressure between cylinder and manifold, for example), the end result will still be the same VOLUME of air, but at a slightly lower pressure than manifold pressure (the ECU has lookup tables of volumetric efficiency multipliers to deal with this).

What if you have a supercharger capable of flowing up to 98,000 L/min at 58 psi, and it's producing 23 psi at 1800 rpm? What's the volumetric flow rate through the engine now? Still 3240 L/minute! The supercharger does not change the volume of the cylinders. And it does not change the engine speed. Therefore it cannot possibly change the volumetric flow rate of air through the engine. It only compresses air, changing its pressure and temperature.

Therefore, two different forced induction systems producing the same boost pressures and intake air temperatures on the same engine at the same engine speed cannot possibly be operating at different volumetric flow rates (CFM, or whatever units you care to use), no matter what their peak boost or peak CFM ratings are.