Yes I have a picture of that installation. It was mounted way too
close to the firewall. Also he had a NACA duct initially but he changed
it at my suggestion and it started working better but not good enough.
Finally he went to the stock cooler and moved it under the engine.
It then had a more or less unobstructed air outlet on the back side.
Paul Lamar
In the picture below it shows exactly what I mean:
It seems to be the typ of oil cooler that is single pass (looks like the
ones Robinson also uses in its helicopters, Steward-Warner, South Wind
Inc.). If it does not get bled correctly it will trap air, at least if
installed like below!
Now two questions for the physics-up to date!:
Lets say the oil goes only to 1/4 of the hight of the cooler at 1 bar. What
oil-pressure do the 13Bīs run? How much would this compress the air in the
cooler at roomtemp.? How much more cooler cross section would now be
available for cooling?
How much would the resulting smaller air volume re-expand when things get
hot (what is the regular inlet temp for the cooler?)
Robinson installs the coolers flat (horizontal), which means air could/does
get trapped for less than half of the width of the cooler. Maybe this
position would help to finally force the air out. Still inlet and outlet
lines turn down immediately after they leave the cooler.
Does anyone have any connections (engineering or so...) to any cooler
makers? They should know best!
Thomas J.
13B's non racing run up to 90 psi. That sounds plausible for a single
pass oil cooler but most if not all Mazda oil coolers are two pass.
Paul Lamar
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