Bruno, I almost didn't say anything but, what the heck.
(Sorry if I'm intruding
)
In your analogy of the two Chevy 305s just substitute in a 350 vs. the 305. More torque? (It's just an open question
)
Not a whole lot more displacement...
Back to the RPM figs. Yeah, that .40 sure can run! I have no doubt it is a great engine. Look what happens after 13600 RPMs. The torque starts dropping. It would seem from Dave G.'s review that the 'torque band' one should try to keep this engine in is between the RPMs 12.5K and 14.5K. If that little gem is turning 12K static with an APC 12X4 what's going to happen when the prop unloads and the engine revs up past 14K? Maybe all of the previous torque wouldn't be necessary at that point- I don't know...
I don't have a review of the Pro .46 to compare the .40's to.
I don't think I'd use it to haul around a 5-6.5lb. plane with though. A fun fly or light plane - you bet!
All I'm offering here is a slightly different perspective.
I'd like to have one to experiment with - that's for sure!
Whatever you decide on - best of luck!
If you do get the Pro .40 let us know how it goes! Definately!
Jeff