Claude most if not all the current 30-35cc gas engines will turn this prop well. That should be a good prop for breaking in the 35, but keep in mindthe engine will turn more load especially on pipe. As far as more power than the YS170, I'm not so sure. I will put a pipe on mine soon and see how it behaves, turning the same props as the YS170 does

To me, high revving is not what we want. My SAP180 HP was high revving and it turned this size prop too but it wasn't as easy to fly well, spooling up to well over 8000....

What I've been looking for is a moderate rpm engine with lots of low end tork turning large disc areas and creating lots of thrust at lower rpm. The OS has that.....that's what I'm saying.

But it's great that more and more people are giving this type of powerplant a good look. It's worth a really good look. Just yesterday I saw the price of Cool Power 30% heli blend; $40 US per gallon would make anyone cringe. Pricing elsewhere (OUS) has to be even greater. That'sabout twice asexpensive than running electric batteries on a per flight basis (assume 100 flights per $200 F3AU battery set)