wuzak
Captain
Here I disagree. Only the lower Prop axis of an inverted V-engine allowed the use of an annual radiator. I don't know any plane with an upright V-engine which had an annual radiator
cimmex
That is not the case at all.
In the case of both the upright and inverted vees, at least of WW2 vintage, the prop drive tended to be offset to the centre of the frontal area of the engine. There is nothing precluding the use of an annular radiator with an upright V-12.
The V-12s with annular radiators in the 1920s didn't, in reality have annular radiators - they had car type radiators mounted ahead of the engine with the prop drive through the radiator.