Originally Posted by
hogflyer
I do have a NIB Magnum .15XLS for my Sig Lil' Extra that may be a better bet. I suspect that .15 XLS will have as much power as a 30+ year old OS .20 and it may end up being a bolt-in swap or require less modification to fit
Oooh, don't diss the old-school stuff...
The older engines will swing larger props without any complaint, while the newer more "powerful" engines will need a smaller prop.
As an example, a 30 year old, baffle piston, Veco .19BB will swing a 9x4 prop at around 12500rpm all day, while the .15XLS will not take anything larger than an 8x4 and deliver around 15000rpm. The XLS would in fact be even happier on a 7x4 prop. So depending on the plane, the old-school stuff still serves a purpose.
Looking at the pictures, I'd say keep it old-school...