Does anyone know the difference in performance of a prop that has new blades vs. one that has blades that have been overhauled a few times and are at near minimum spec? Is there a rule of thumb? Thanks for any thoughts.......

I havent heard any noticable performance loss. I have run blades down to the last overhaul and when new ones were installed at $1800 per blade x 3 I didnt see a kick in the pants improvement in performance. Just a lighter walet. After I dress out the nicks, polish and paint my gravel beaten blades it feels smoother. Like a freshly washed and waxed car feels faster.

I had the prop on my C-170 overhauled years ago (IA said it needed to be done) and what I noticed were smoother running at all RPM and lower RPM on final for same airspeed.

This isn't a total high jack, and.....I found it interesting.

When Mark Dusenberry built his 1905 Wright Flyer replica, he had to make two 9 foot wooden propellers that needed to put out equal power. He bolted down the plane in the hangar and hung two simple bathroom scales on the wall right behind the plane's pusher props. He would run the engine up and take readings from the scales. Then he would carve on which ever blade need tweaking.

I'm told that if the profile is reduced (ie cutting nicks out of the leading edge, etc) that not much performance is lost. If the tips have been cut down, making the blade shorter, than noticeable performance can be lost, depending on the air frame. A longer prop is best for high drag air frames while slick ones do well with shorter props turning high rpm.