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I would suggest that you're looking at a manifestation of adiabatic
cooling. As air rises in the atmosphere, it cools at the standard adiabatic
rate of 3 deg F or 2 deg C per 1000'. That's equivalent to 3 deg F per inch
of manifold vacuum. Idle at 2000 rpm can generate around 15" of manifold
vacuum and that converts to 45 deg F temperature drop. That is waaaaaaay
more than the dew point spread in most places. A lot of the heat (and
therefore temp drop) gets absorbed by the warm environment, but not all. It
is the same phenomenon that causes carb ice.
Just a theory .... Jim S.
Rino wrote:
An interresting observation about my turbo 13b installation.
While running the engine to check out the systems I noticed that my
intake runners become real cold, actually they sweat from the
condensation on the outside.
I have an intercooler but there was no airflow through it since the prop
is not installed yet.
I reason that the air is compressed by the turbo -- heated up then had
time to cool a bit before getting into the intake manifold where it
would expand and cool rapidly and would cool the intake runners.
The intake runners were very cold to the touch.
The engine was running idle to about 2000 rpm at the time.
Rino
>> Homepage: http://www.flyrotary.com/
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--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T
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