Results 1 to 7 of 7
  1. #1
    Boilerman Bill BPnta's Avatar
    Join Date
    Jun 2008
    Location
    Yulee, FL
    Posts
    887
    +1
    1

    Leading edge relaionship to Trailing edge

    To all the pump pros out there!!

    How much does 1 degree on the leading edge equal to a change on the trailing edge??

    For instance I have a 13/25 on my setup that runs good but want more holeshot. Would the 14/21 keep my RPMs about the same?


  2. #2

    Join Date
    Jul 2005
    Location
    Central North Carolina
    Posts
    3,846
    +1
    527

    Thumbs up

    re pitch the prop to a 12/25 for more hole shot and still keep the same rpm on top, Tommy Jordan

  3. #3
    hitman's Avatar
    Join Date
    Aug 2006
    Location
    Ft. Lauderdale, FL
    Posts
    4,328
    +1
    12
    Quote Originally Posted by 2fast4u View Post
    re pitch the prop to a 12/25 for more hole shot and still keep the same rpm on top, Tommy Jordan
    Is this for a standard swirl or DF prop? Also for the SHO or FZ? Sorry for all the questions. It just seems that the FZ and SHO have different results with the same prop. I guess it's becasue of the bigger water inlet on the FZ???

  4. #4

    Join Date
    Jul 2005
    Location
    Central North Carolina
    Posts
    3,846
    +1
    527

    Thumbs up

    Quote Originally Posted by hitman View Post
    Is this for a standard swirl or DF prop? Also for the SHO or FZ? Sorry for all the questions. It just seems that the FZ and SHO have different results with the same prop. I guess it's becasue of the bigger water inlet on the FZ???
    same for all variable pitch props, The first number is the starting edge of the impeller and the last number is the trailing end of the prop the lower number on the front the better the accleration and the higher number is the pitch on the trailing end of the impeller for top rpm/speed. Example a 12/ 21 would acclerate better than a 14/21 but the top speed would be about the same. A variable pitch impeller is designed to have the best of both worlds good accleration as well as top speed. where as a straight pitch prop a (21 pitch only from starting to trailing edge) would suffer with poor acceleration but the top speed would be ok. Tommy Jordan

  5. #5
    Boilerman Bill BPnta's Avatar
    Join Date
    Jun 2008
    Location
    Yulee, FL
    Posts
    887
    +1
    1
    Quote Originally Posted by 2fast4u View Post
    same for all variable pitch props, The first number is the starting edge of the impeller and the last number is the trailing end of the prop the lower number on the front the better the accleration and the higher number is the pitch on the trailing end of the impeller for top rpm/speed. Example a 12/ 21 would acclerate better than a 14/21 but the top speed would be about the same. A variable pitch impeller is designed to have the best of both worlds good accleration as well as top speed. where as a straight pitch prop a (21 pitch only from starting to trailing edge) would suffer with poor acceleration but the top speed would be ok. Tommy Jordan
    If the 12/21 accelerates better and has a close top speed, what are the benefits to running a 14/21?

  6. #6
    I would say he needs more than a 12/21 he is going to cavitate like crazy...I would think best holeshot would be at the point when the cavitation goes away and you are not on the rev limit...

  7. #7
    hitman's Avatar
    Join Date
    Aug 2006
    Location
    Ft. Lauderdale, FL
    Posts
    4,328
    +1
    12
    I just installed my brand new skat 13/23 in my SHO and took it out on the river yesterday. Before that I was running my stock 12/20 repitched to 12/23. I would say that I might have lost a little bit in acceleration with the new 13/23 but the AWFUL cavitation on hole shot is gone. Also I could really feel acceleration and top and pick up as I got lower on fuel. Guess the new prop is right on the edge of being too much for me to turn, so now, I can really notice a little extra weight in the front end.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. At what point to I need to add pitch to the LEADING EDGE
    By Boost Almighty in forum Yamaha PWC Performance (4-stroke)
    Replies: 7
    Last Post: 09-12-2013, 11:42 AM
  2. Impeller leading edge and trailing edge question
    By pdxrealtor in forum 4-Tec Performance
    Replies: 36
    Last Post: 10-13-2009, 08:23 PM
  3. leading edge trailing edge
    By mmvane2 in forum 4-Tec Performance
    Replies: 2
    Last Post: 05-29-2008, 01:48 PM
  4. The leading edge?
    By suck my wake in forum 4-Tec Performance
    Replies: 5
    Last Post: 10-10-2007, 12:27 PM
  5. Leading edge of Impeller cut back
    By kevski in forum Yamaha PWC Performance (2-stroke)
    Replies: 12
    Last Post: 01-17-2006, 09:54 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •