Comments by "" (@EbenBransome) on "Imperial War Museums" channel.

What did for the Germans was a shortage of critical materials, nickel, manganese, cobalt,chromium, meaning that their engines were limited in power by valve burn. It wasn't helped with the D-B engines by cylinder head design defects which worsened the valve problem. The invasion of Morocco was to deny the Germans cobalt and tin and was highly successful in crippling their aircraft engine design. That with (eventually) bombing the fuel production plants was what did for the Luftwaffe.
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@honkhonkler7732 It wasn't modified for mass production, this is a myth. It was modified to suit the US preference for off the shelf machine tools. RR used mass production but they had dedicated tools for each part. The myth seems to have arisen when Packard got some prototype engines from the UK and thought they were production versions. RR made more engines than Packard.
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