Note: the exhaust area requirement is greater than the inlet
combination of oil and coolant due to the now considerable hotter air
temperature. Rule of thumb: Coolant air inlet opening for 200 HP
coolant cooled engine ~60 sq. in., oil inlet opening ~30 sq. in. equals a total
opening of 90 sq. in. A good place to start with exhaust opening is 1.4
times the inlets or 126 sq. in. Close the exit area down with cowl flaps
to as little as 80% of the inlet combination at cruise conditions!
Thanks for the
rules of thumb Doug. I think something like this can be more help
to a new builder than all the math in the world, but we will have to make
sure the rule of thumb matches reality pretty
well.
I was just
making a note in my log about the current inlet and outlet sizes, and decided to
compare them to the ones you posted. Here's the log note, just as a point
of reference.
As
an added note, the cowl exit area now measures 6.5” tall, and an average of
about 19” wide. This gives 123.5 sq
inches of exit area, where the stock cowl exit was about 76 sq inches. The cowl cheek inlets are about 24
sq in each, for 48 sq in total for coolant (throttle body takes air from this
was well). The current oil scoop is
30 sq in, and I suspect (hope) it’s going to be too big.
Cheers,
Rusty (being
flooded from the new house built on a $%@& mound next to us
grrrrr)