prop size
 

i have a rude 120 my mechanic just gave me a 13x19 ss prop is that a good match and what shale i expect i have a alum prop now

You will definitley come out of the hole quicker, but not too sure about top end speed. SS props have much less flex and pushes more water. What size prop are you running now?

Even with the smaller dia I'll bet that a 19 pitch prop is simply not going to be a good prop for your engine. Way too much pitch. I'm thinking more in the 15 - 17 pitch range. And my bet would be on the 15P. Aluminum would be a 17... SS would be a 15. :head:

13.5X15 stainless will be about as big a prop as you want to run. That lower unit has a 2:1 gear ratio, and the 120 is a high RPM engine. A 19 pitch stainless will lug it down and possibly cause a powerhead failure. I would be surprised if it will get on plane with a heavy hull like a V-20 if it is indeed a 19 pitch prop. I know I ran a 19 pitch VIPER on my 140 on a 19 foot bowrider and topped out 56 MPH at 5600 after it was recupped. A 17 pitch stainless prop topped out at 49MPH on teh same boat at 6100RPM's(which was my rev limiter). A 15 pitch stainless is what I ran on the same engine on a 19 foot ANGLER center console and it ran pretty good.

prop size
 

the prop is a used prop my mechanic gave me because the old prop blew the bushing. i bought the motor from him and he gave me a 90 day warranty. the prop was written on with a paint marker 13x19R so i assumed its 13" x 19* right rotation prop i am not sure what size prop was on it before. i took it out once since i got the motor and when i slowed the boat down then went to speed back up it seemed as if it was not in gear but it was going slow but motor was wide open so i told the mechanic and he suggested to change prop

i ude to run a 15 alum on my v, went great for me!!