I just reshaped my bottom cowl to fit the radiator.

    What size inlet in relation to rad size should I start with, 10% or 15%
    of rad size. 10% will be a 34.3 sq inch inlet which is already a pretty
    big hole to cut for one side. There's insufficient distance to do a
    masterful job with a diffuser up to the wedge itself going on the rad.

    Alex Molteno

    Keep it the same size to start. Your cross counter flow rad is more
    efficient than
    the old 3 inch thick core with that rule of thumb. You can always make
    it bigger later.

    Think about the outlet lovers. Here are some nice ones from Lewis Bjork.

    Adjustable ones are best.

    Paul Lamar

    If you reorient the opening to a vertical slot like Lewis did it makes the transition
    to the K & L wedge diffuser easier. Here is another picture of that.

    BTW Alex I don't think I have any pictures of your actual rad mounting.
    Will you please send me some.

    Paul Lamar



I built a wood frame to the dimensions of the cross counter rad, to use while doing the bottom cowl work, the rad isn't installed yet, I'll send some photos when its mounted up.

The vertical slot will work better for the intake.

I was also thinking of doing a 3 into 1 exhaust collecting into a 2" pipe and running that into a 3" pipe to get some exhaust suction out the cowl to help with oil cooling. On page 67 of your book it says a 1.4 diameter ratio ejector will work well for cooling airflow, which is roughly what a 2" into 3" pipe will give.

Alex Molteno



Here are some 3D's for the new guys
The upper right motor mount needs to be moved inboard for clearance.
No problem on a composite air plane.


Paul Lamar


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