Hi Paul
I am not quite sure how to deal with turbo, venturi restriction and exhaust
restriction
but your number of 87,700 cfm seems quite off.
Lets take a simple look at the 914 as a simple air pump not developing any
pressure.
We need to keep in mind that since it is a four stroke, you only intake
the displacement once every other revolution. Thus you only intake 1/2 of the
1211cc displacement every revolution (two full breaths of the four) or 605.5cc
per revolution.
Now lets take 5100rpm and multiply it 605.5cc to give us the cc per minute of
air
pumped, then multiply it by conversion number of .000035314 to convert cc to
cf. That gives us a tad over 109 cfm.
Not sure what you are after, but a 650cfm carb is quite a big beast compared to
the ability of two type 64 Bing carbs. I can't imagine how large an engine would
be that could handle a 87,700cfm carb, but then again you are looking for
something else? Exhaust design? Or?
You could always measure the exhaust of engine running at that power setting.
Take
several sheets of large plastic and make an enclosure. Calculate internal
area and plumb your exhaust to it and time to fill.
Now if you are talking about how many cfm of air the propellor could flow at 30"
and 5100rpm with your Airmaster "ground loop" adjustible prop, perhaps the 87K
is a lot closer. A 10hp motor running a 30" prop may push perhaps 20 or 25K
of air per minute at a very low pressure. My basis for this estimate is my
homebuilt
balloon is 95,036cf and I can fill it in under 4 minutes, but then there
is some spill out from the 15 foot diameter mouth.
Hope that helps.
Ron Parigoris
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