Bulent Aliev wrote:
Paul, how are you cooling the oil cooler with this system?
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Bulent Aliev
Stretched CZ MK-IV W/Turbo Rotary And Big Ass P-51 scoop:)
Ft Lauderdale, FL FXE
I would mount the stock Mazda oil cooler long ways alongside the rad.
No need to change your system as long as you take the air in on
top of the rad and dump it out the bottom.
In effect it is exactly the same as the new system.
Paul Lamar
I don't understand why take the air from the top and force it down? The
natural path of the heated air would be from the bottom up by convection.
Bulent
True but the oil pan is too close to the back of the rad.
Any time moving air impinges on a more or less flat surface pressure
is generated. This back pressure impedes the flow of air through
the rad. In my van test with a two inch thick rad in this configuration
the speed of the air flowing through the 2" core is about 40% of the
forward speed of the airplane. As a rough guess that could reduce
the flow through the rad by about 25%. That percentage will be higher
with a thinner rad.
Here are some K&M graphs of data on the subject. According to these graphs
the rad needs to be about 10 inches below the oil pan if the
air is allowed to flow up through the rad. There is just not enough
room in the cowl to do that. Therefor it is best to have the air flow
down through the rad and directly to the outside as Perry has done.
The wedge shaped diffuser is only four inches high at it's highest
and zero at the end of the rad.
I just uploaded pictures of Gary Spencer's rad too close under the
engine and pictures of Perry correct rad installation and air outlet.
BTW almost all air cooled aircraft engines use down draft cooling
so natural convection obviously is a minor consideration. In other
words the normal high flow of cooling air overwhelms the the
natural convection.
Paul Lamar
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