electric superchargers

[Jeremy Edmondson]

Ed Mellinger wrote:
> 
> A little back-of-the-envelope arithmetic:
> 
> Your 3 liter 4 stroke eats 1.5 liters of air per revolution, 3000 liters
> per minute at 6000 rpm, or 150 liters/sec.  That's .15 cubic meter/sec.
> 
> 5 psi boost is about 35 kilopascals which is also 35 kilonewtons per
> square meter.
> 
> Multiply .15 m**3/sec times 35,000 N/m**2 and you've got 5,200 N-m/sec
> after you cancel the units.  Often called "PV Work".


You neglected to include the fact that in order to get a boost pressure you need to pump more air 
than the engine displaces.  Air is compressible remember.  The volumetric flow rate is in this case:

(136.3e3/101.3e3)*0.15=0.202m^3/s

=> P=0.202*35e3=7kw
               =9.4hp