3 blade to 4 blade help

[Mattyp11]

I have a 1986 Winner zz880 with a 1990 Johnson 150 that runs like a top. The 14.5x19P aluminum that came with it is pretty banged up, and I'd like to try a 4 blade for handling, hole shot, porpoising and just cuz. The Turning Point website, after entering the exact specs of my boat, gave me options of a 14x17P for pulling/loads and a 14x19P for speed. Also I'm at altitude. I thought going down 2" in pitch was common rule of thumb. My RPM at WOT is slightly under 5000 at about 45 MPH right now fully loaded. Will keeping the same pitch of 19P really keep me at top speed without too much RPM loss? Or should I drop to 17P?
Thoughts and opinions appreciated. I do realize without actually testing it, I won't know for sure what I prefer. Just looking to see what everyone thinks I should try first.

-Matt

 

[alldodge]

Rule of thumb going from 3 to 4 blade you drop 2 inches of pitch.

Your current 19 being banged up will also not hold as well as one which is in good condition. So if you had a good 19 your WOT rpm may be lower. Just something to think about

 

[Mattyp11]

Cool thanks. I think I'll go with the 17p. Especially since I'm at 5000 feet at home, and sometimes boat at 9000!

 

[QBhoy]

Could go either way for me. Especially after some testing going from a 4 blade to a 3 blade today. The 3 blade of 2” less pitch than the previous 4 blade showed lower rpm all the way through the rpm. Didn’t play by the usual rules at all.

 

[Selleck95]

I would recommend another brand. I have been trying turning point props for about three weeks and have come to the conclusion they are not great props. I have tried three and four blade of different pitches and my prop slip and performance is less than ideal.