"Bob F." wrote

Here's a question ...
When a normally aspirated engine quits while at cruise, how does the MAP
react with respect to the throttle?
Does it indicate zero?
Does it indicate barometric pressure?
Does it pin? (Go to max)?
Does it follow the Throttle (high MAP with a high throttle setting , low
when set to low throttle setting)?

From a theoretical point of view, I vote for the last choice. Why?

I would think because, if the prop is still turning, the engine is still an
air pump, just as much so as if it were still running. The "suck" part of
the suck, squeeze, bang and blow is still there. If the throttle is closed,
the throttle butterfly is closed so the suck is trying to pull a partial
vacuum.

I would think that because the engine is turning more slowly, the ability to
pull as low of a MAP will be lessened, (higher MAP-just to clarify) than the
pressure you would normally see at the same throttle setting with the engine
running.
--
Jim in NC