FLYBOYJ
"THE GREAT GAZOO"
Not that much, radials and inline do not weight that much differently. The bare engines yes, but considering the numerous cooling stuff the inlines require as extra... they are almost the same weight.
Look at the weights of radials that put out above 1200 hp. There's a curve and it goes up drastically with horsepower. Low HP radials are the ones for good weight to power ratios....