S!
Thank you for the update
Nice to see things shaping up. In that DB605 video you can see the root of the flame has reddish/yellow but the tip of it is blueish. Could the British and German difference be that Brits and other allies had carburettors and Germans had direct fuel injection in their DB/Jumo/BMW engines. The mixture in a fuel injected engine, like DB-series, is better than in a carburettor engine and high pressure spray of fuel gives more even fill of the cylinder at the right time compared to the suction in a carburettor system.
Also many nightfighter books I have read state blueish flames on British bombers. And there was a talk witha guy who tuned/maintained DB engines and he said the engine tunes were done in a dark room to see the exhaust flame color to adjust the injection etc. correctly.
Ok, have a good weekend all!