Turbo Bypass

[goflo at pacbell.net]

Zack wrote:
          Cartech, for example, makes
> intercoolers for GN's with the following specs:
> 
> "The intercooler has less than 0.6 psi
> pressure drop across the core at 17 psi with an efficiency rating of
> 90%"
> Now, even the most spectacularly efficient turbocharger is going to
> have an outlet temperature somewhere in the vicinity of 300 degrees F
> when running 17 psi of boost if the ambient air temp is 80 degrees.
> This 90% efficient intercooler will reduce that temperature back to
> 102 F at it's outlet.  In absolute temperature, the inlet is at 792
> degrees Rankine and the outlet is at 594...  the absolute outlet temp
> is ~75% of the inlet temp.  Blindly apply PV=nRT to this situation,
> given that the inlet pressure (absolute) is 31.7 PSI, and you'll come
> to the conclusion that the minimum pressure drop across the
> intercooler must be 7.9 PSI.
>         That is not just a little wrong, that's -totally- wrong.  Off by a
> more than factor of ten.  QED.

I'm under the impression that the figure of .6 psi represents the static
restriction of the device. i.e. (17-.6)/17 ~ 96% volumetric efficiency.

Regards, Jack