What all of these proposals miss is an actual driver to make it happen .
For example ;
Just as the Bristol Beaufighter reached squadron service the Factory making the Hercules engine was hit by a raid and all production drawings and much of the factory was destroyed .
In desperation the Bristol Engineers built a franken engine with 2 Bristol Pegasus radials in one cowling . Initially the single propeller was seen as the easiest option however reality was it developed vibration . In an effort to fix this problem a contra rotating propeller was fitted to each engine assembly . The new franken engine was 40% longer and resulted in a change in nacelle design to bring the CG back to an appropriate point . The new engine produced 1800 hp at sea level and 1600 hp on a continuous climb setting . The new contra rotating propeller also improved engine out performance . The extra 400 hp improved all aspects of flight performance .
Was that using standard Pegasus components or did it need modified components?
What was the weight of the engine?