[XByoot]

Pretty sure the Allison only ran a single speed blower hence the need for the turbo compound system I guess. The later Merlin’s ran a two speed blower for better altitude performance. The Wright 3350 used PRT ( power recovery turbines) that were exhaust driven and coupled back to the power section via some kind of fluid coupling , they didn’t actually provide any form of boost to the intake, they had a two speed blower to take care of that. They also ran a low tension ignition system, which is a coil per plug arrangement. This allowed a shorter run of high tension cables and less prone to failure at high altitude low pressure environments, basically a coil near plug system as we know it today. Another interesting discovery was jet streams, cores of high speed winds at high altitudes. Many planes were lost or had navigational difficulties due to them having super fast or slow ground speeds. Sorry for the ramble...I love this stuff!