Frank’s smaller pitch Cyclone prop is a 4B prop with heavily cupped blades, so it’s a totally different animal with much more blade area than the 3B Viper. The Viper is BRP’s “speed” prop which may provide the highest top speed, but it doesn’t have a lot of stern lift, so it won’t hang on plane at low speed as well as a 4B in my experience. Not all props are created equal either, so you have to consider the prop’s design intent . . . some have small blades with lots of cup that are designed to run at high speeds very close to the surface, while others are designed with large blades for heavy loads at lower speeds. BRP’s Rebel is a 3B prop, but it has very large blades with lot’s of cup, so it typically acts like it has a couple inches more pitch than advertised! A dealer told me the Rebel was so hard to turn on a boat like the Seafari that it was not normally used on the small block 60 degree V-6 2.7L motors like the 150/175/200 E-TECs; it’s typically used on the larger 3.3L 225/250/275 hp motors.
Since you currently have so many unknowns (tach accuracy, WOT speed with current prop, motor height, min planing speed with current prop), I would stick to an inexpensive aluminum prop that can be easily repitched if you later find it produces too much or too little max rpm. Once you have decided what performance characteristics are most important to you (max stern lift/cruise fuel economy and minimum planing speed or strong hole shot for water skiing OR max WOT speed) then you can select a prop design that best meets your requirements. I tested a lot of props on my Seafari with a 150 E-TEC/bracket and found that a 4B 14.5x15 Cyclone was the best, but I had to raise the motor about 4” with a jack plate before it would reach max rated rpm. That prop was harder to turn than a 4B 15x15 Michigan Apollo with the same blade area because of the heavy cup on the Cyclone blades. In general, I found that the 4B props provided much more stern lift that helped me to hang on plane at lower speeds than the 3B props, and that is a very significant benefit!
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