Paul Leidl in Minnesota has an IO-240B Series 5 on floats, haven't heard from
him in years on the forum, but if he's out there he would know. I like my
airplane with IO-240B and at light weight it is a rocket, BUT my impression is
the wing doesn't work well at heavy weight, and that sucks all the performance
out of the plane.
Here's my thoughts after 10+ years flying my Series 5 with an IO-240B, and
I do not have performance problems with mine. I can get close to 2000 fpm
on a good day solo, and I can hit VNE in level flight at full power.
Light weight with IO-240B I get very good performance, heavy, it's not as bad
as a C-150, but I would not call it good either. The original SkyStar sales video
where they say if "you ever wanted to fly the bush in a SuperCub, have we
got a plane for you ..." is a bit BS. Put a load in the plane and get near max
weight, it flies terrible. It is a truck with a heavy load.
I think the 912 weight engine probably works better in the air frame ... I
personally think it's the airfoil, and it works poorly at higher loadings. I'm
sure somebody will dispute this, but that's what I believe.
The other thing is the fuselage length is too short relative to the wingspan,
and it causes a lot of the constant annoying rudder pedaling you have to
do on a choppy day. I used to build and fly RC Sailplanes, and the Kitfox does
exactly the same thing, which in an RC Sailplane I would have fixed by
making it longer.
Next I would not put floats on my airplane with IO-240B since I know the
weight would kill it.
Jeff