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Old August 28th 07, 11:25 PM posted to rec.aviation.owning
Michael[_1_]
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Posts: 185
Default Mixture--science vs witchcraft?

On Aug 26, 6:53 pm, wrote:
...but it does bring up an interesting point. One that I have yet to see adequately explained anywhere. I've seen a
few engine operating curves that limit max manifold pressure as a function of RPM, there are many that don't. My fixed-pitch
Cherokee doesn't have the option, but I'd be interested to know any source that explains it adequately.


The main reason such a chart is not universal is because there is no
requirement to publish such a chart, not because it's not relevant. I
suppose there might be a (horizontally opposed) engine installation
out there that will comfortably run at sea level with the throttle
control all the way forward and the prop control all the way back, but
I doubt this is the norm.

While few manufacturers provide a limit chart, most provide
recommended power settings (generally with quite a few 'oversquare'
options) and other guidelines (for example: Do not exceed 25" MP at
2000 RPM or less).

Michael