Piston engines 101-a : When a pilot says his aircraft manifold pressure goes to "zero" on a gauge that only goes down to 10, he is really saying that his MP went to what amounts to .33 bar's. Well within the probability of compression braking caused by intake obstruction. Zero is a euphemism for "bottom of the gauge ".
And as for any inference that a piston engine can not " run" at less than 12"MP, once again this misses the point. If an aircraft is "flying" and the prop is spinning, engine is "running" but not producing power . Thereby the MP can easily indicate less than 12" of merc, provided that the induction side is somehow constrained.
And / or it wasn't powerful enough.
Last edited by Roger : 01-10-12 at 10:44 PM.
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