The price 2015 Corvette C7 Z06 pays for using small supercharger

What really sets 2015 Corvette C7 Z06 from previous Corvette ZR1 is not the extra weight or shitty aerodynamics.  What really sets this car apart is the small supercharger.

What could possibly motivate +Tadge Juechter and +General Motors to use such a tiny supercharger on the Corvette flagship?

Before speculating about the GM motivation, there is one thing that should be clarified first: the supercharger efficiency.  A common wisdom would associate supercharger efficiency with the amount of air it can flow but this actually would be a very flawed assumption.

Efficiency of anything is always what comes out versus what goes in but... superchargers have a very peculiar constraint: the speed of rotation and thus, there are actually two efficiencies that should be evaluated: low and high speed efficiency.

At low rotational speed, superchargers tend to leak, it is a given.  The faster the supercharger spins, the lower the leakage will be (due to higher flow rates). 

And here lies the false assumption that low rotation condition of higher efficiency can be synonymous with the overall efficiency of the supercharger.

What are other advantages of smaller supercharger, especially of a positive displacement variety?  The smaller rotor diameter means a smaller rotational inertia resulting in smaller power demand and better instantaneous response at lower RPMs, resulting in better off the line performance and better responsiveness in the low RPM range.

Finally, there is also a matter of lesser cost involved and potential for "weight savings".  Considering that new Z06 prices comfortably reside in six figure digits even at MSRP and that the car is a true porker even without automatic transmission and convertible version, everyone should know how this part worked out...

Sounds like a winner and great credit owed to Juechter for forward thinking?  Well, not exactly...

Here lies the biggest problem and it is directly related to the higher RPM efficiency and price that has to be paid for improving the lower end: while the boost is virtually the same 9.4 vs. 9.7, the maximum boost is achieved at over 5k more RPMs!!!  What is the problem here?  Those pesky laws of physics and thermodynamics get in the way of smaller supercharger. 

As the RPMs increase, while the supercharger does work to pump and compress the air, the heat is generated and the faster the rotor spins, the more heat is generated.  As the air is heated up, its density decreases (again due to those pesky laws of physics and ever present friction) and so does its oxygen content.  Of course less dense air compresses more and poof, goes the boost.

Now, observing what the buyers of the Z06 experience, having this porker literally run out of steam at higher speed and RPM, there should be little doubt that this is exactly what is happening, in spite of the improved intercooler, flow rates and low IAT.

Could the smaller supercharger work?  Of course it could but the car would have to be more aerodynamic and lighter.  Considering the new Z06 fails on both of these accounts, Juechter did the dumbest possible thing, ignoring the basic facts.  The results can already be seen.