I was reading about the RR V12s and had a thought that radial engines were perhaps a sort of WW1 relic, but apparently not. The plane that holds the piston engine speed record is a modified Grumman Bearcat with a 46 liter 18 cylinder radial engine. The Bearcat doesn't look as cool as the Mustang or the Spitfire - the radial engine gives a more squat look, but apparently it had it's good points. Not introduced into service until 1945, it's legacy is sort of muted.
https://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-2800_Double_Wasp#Specifications_(R-2800-54)
The BMW fighter engines also radial. Makes sense for an airplane.