109 e3b against spitfire II

[Viper2000]

Quite.

To a lesser degree the same argument applies to British engines, given that the most successful airliner airframes were American in 1945. Therefore comparison between the Merlin and the R-2800, R-3350 or R-4360 in the civil market isn't really fair; it makes more sense to compare it with the Bristol Hercules or Centaurus, and if you perform that comparison then the Merlin doesn't look quite so much of a "failure" in the civil market anymore...