When do I need a 17-4 pump shaft?
+ Reply to Thread
Results 1 to 9 of 9

Thread:
When do I need a 17-4 pump shaft?

  1. #1
    Senior Member stewvette's Avatar
    Join Date
    Nov 2009
    Posts
    123

    Default When do I need a 17-4 pump shaft?

    I did a quick search but couldn't find anything on horsepower or rpm levels at which you need to upgrade the pump shaft. Is there a way to tell the standard and performance shafts apart visibly or otherwise?
    Thanks

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Boat Nut sleekcrafter's Avatar
    Join Date
    Dec 2007
    Location
    South Elgin, Il.
    Posts
    5,131

    Default

    17-4 are the newer HP shafts, the older HP AQ's were magnetic, the old standard shafts were hard chromed for the bushing. Some where around 500HP is the number, mostly it's how abusive you are to the pump really determines the HP cut off.
    Upper Midwest Power Boat Association
    DRAG BOAT RACING UMPBA #926


  4. #3
    Senior Member jetboatperformance's Avatar
    Join Date
    Dec 2007
    Location
    Atascadero Calif
    Posts
    7,464

    Default

    Quote Originally Posted by stewvette View Post
    I did a quick search but couldn't find anything on horsepower or rpm levels at which you need to upgrade the pump shaft. Is there a way to tell the standard and performance shafts apart visibly or otherwise?
    Thanks
    Alot depends on what you will do with the boat , and like Chuck indicated ,how much HP , you may be surprized to find a modern high strength shaft is very comparable in price to a stock replacement shaft Tom

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Ain't Right Racin piston in the wind's Avatar
    Join Date
    Dec 2010
    Location
    Sapulpa ok
    Posts
    1,706

    Default

    I bet they will hold 900- 1000 hp as long as it isn't loading and unloading the pump

  7. #5
    Senior Member
    Join Date
    Feb 2008
    Posts
    546

    Default shaft info

    chuck and tom have vast experience on these shafts and both gave good answers, my engineer book list the 304 as a yield strength of 31,200 psi and the 17-4 as 145,000 the elongation of 30% and 5% respectively, obviously the 17-4 is much much stronger, have seen some of the 304 twisted like a barber pole with 350 horse engines , this caused by jumping ways and slamming the impellor,, sledom see the 17-4 shafts damaged, like tom stated depends a lot on how you use the boat and if you are replacing the shaft not much difference in the price, if ever intended using bronze or stainless impellor the 17-4 is no where near as likely to warp.

  8. #6
    Jackwagon Patrolman Rexone's Avatar
    Join Date
    Dec 2007
    Location
    The Earth
    Posts
    11,644
    Blog Entries
    24

    Default

    17-4 is the magnetic material, it is very close to Aquamet's strength but substantially less $$.

  9. #7
    Senior Member stewvette's Avatar
    Join Date
    Nov 2009
    Posts
    123

    Default

    thanks for all the input guys.. I'm building 750- 800 horse blower motor and its going in a lake boat that will occasionally see some rough water so a better shaft will most likely be needed. I took a quick look at the shaft a magnet will not stick, so anything else i should look for to see if it might be an upgraded shaft being that the boat already had a blower motor?

  10. #8
    Jackwagon Patrolman Rexone's Avatar
    Join Date
    Dec 2007
    Location
    The Earth
    Posts
    11,644
    Blog Entries
    24

    Default

    Quote Originally Posted by stewvette View Post
    thanks for all the input guys.. I'm building 750- 800 horse blower motor and its going in a lake boat that will occasionally see some rough water so a better shaft will most likely be needed. I took a quick look at the shaft a magnet will not stick, so anything else i should look for to see if it might be an upgraded shaft being that the boat already had a blower motor?
    You could have a metalurgist test the shaft. From a practical perspective if it was running for any length of time with the blower motor under load and didn't twist or break its likely not a stock shaft, more likely AQ (being its not magnetic). That isn't a guarantee certainly though. Lots of variables.

  11. #9
    Member
    Join Date
    Apr 2011
    Posts
    37

    Default

    Quote Originally Posted by johnray069 View Post
    chuck and tom have vast experience on these shafts and both gave good answers, my engineer book list the 304 as a yield strength of 31,200 psi and the 17-4 as 145,000 the elongation of 30% and 5% respectively, obviously the 17-4 is much much stronger, have seen some of the 304 twisted like a barber pole with 350 horse engines , this caused by jumping ways and slamming the impellor,, sledom see the 17-4 shafts damaged, like tom stated depends a lot on how you use the boat and if you are replacing the shaft not much difference in the price, if ever intended using bronze or stainless impellor the 17-4 is no where near as likely to warp.
    If you do a mild H.T. you up the numbers more. I always recommended 500 H.P. as the base change point, which we also recommended Impeller change to Mag Bronze or S/S also a 7 to 9 pound Impeller increase also. Aggressors 17-4 had a Mild H.T. FYI
    As cost on Stainless went up we dropped all but 17-4 which also fit the newer bigger torque motors being produced. Cost became so close little cost advantage to produce the lower. The Aqua Marine shaft has much more carbon and less chromium content thus a lower twist strength. It's name came about as it was a special grind on the entire 12' bar with a much tighter tolerance on streight-ness over a 12' foot length for Prop Shafting, thus the additional cost.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in


Tags for this Thread

Digg This Thread

Posting Permissions

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95