Bax, What prop would you recomend for a 91 Surpass II on a not very light 4 Star 60?
Bigcam

We'd use a 13 x 8 or 12 x 10 for basics. You want to run the engine in the mid-9,000's, so any prop that will let the engine turn there and fly your model the way you like is a good prop.

I recently bought an OS 120 Surpass, no pump, and it will be going into a top flite corsair. I want to turn a 3 blade prop. What size would the 120 be comfortable turning?

Any info would be appreciated. Thanks.