Crunk, maybe you're right ?
I am absolutely correct in saying that on a Rolls-Royce Griffon engine the boost (manifold pressure) will be maintained if the engine rpm is unchanged. I
411A and a few others insist that on Pratt and Whitney supercharged engines the manifold pressure will REDUCE even if the rpm is unchanged.
(Both cases assume the is no change to throttle (power lever) position)
To summarise,
1. Aircraft straight and level in cruise
2. Propeller in the constant-speeding range (On speed)
3. Throttle (Thrust lever) set to cruise boost - say +6 lbs (42 " Hg)
4. Power is lost due to either total fuel starvation or both magnetos being switched off
Most people agree that engine rpm will be maintained by the CSU (propeller governor) moving the propeller to a finer (lower) pitch to maintain the selected engine rpm.
Question...........What happens to engine boost (manifold pressure ) and WHY
Is there anyone out there, who understands the question and knows what they're talking about, who can give an explanation for the alleged differences between British and USA engines ?