Greg Copeland wrote:
: Just tossing this out there...

: The final rise in temp is always relative to the ambient air temp. At
: altitude, where temps can be quiet cool, you are getting a modest
: "intercooler" effect. Additionally, amount of boost provided by the turbo
: dramatically effects the temp delta.

: As an example, a turbo pushing 10 psi, with no intercooler, may cause a
: temp delta of 100' F (real world number), measured at the intake. If you
: are at altitude, where ambient is quiet cold, say, 40-50' F., then the
: intake temp, given the same boost, may only be 140-150'. Compare this to
: take off, at sealevel, on a 95' F day, the intake charge may measure ~200'
: F, given the same boost.

10 psi is a lot for a GA aircraft. 5 psi is more typical maximum boost (i.e.
40" MP)

: Turbonormalized is a little bit different because the boost is going to be
: much lower at take off than at altitude...nonetheless, you are still
: getting an intercooler-like effect from the cooler ambient air.

Only in the context of comparing the engine to ground-based racing
applications. In the context of aircraft and density altitude, temperature rise is
temperature rise. Barring unusual thermal lapse rate, the *effective* density
altitude takes into account the decreasing temperature with altitude.

-Cory

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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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