Rex's Hanger just released a video on the Petlyakov Pe-8. Given the extreme political realities of late 1930s Soviet aircraft development, it's amazing that this 4 engine heavy bomber airframe served so long into the Cold War. Regarding Rex's title, maybe glorious failure?
I liked the video, but I wish there had been a real comparison to period 4 engine bombers say in 1937 and 1943. But I know the numerous engine changes have to make performance comparisons difficult.
is there a bomber or fighter that more different engines fitted to it in ww2?
Hawk 75,81,87 is a strong contender.
Including Prototypes it used 4 different radials and two different V-12s.
Depending on how you count the Allison with and without turbos you may be able to stretch that bit
Granted two of the radials were in the mid 30s.