Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 22
  1. #1

    Pump tunnel testing....

    I installed a gauge and fitting on my pump and tested to see what kind of pump pressure Im getting at 90mph. Currently running between 50-55 psi at wot...This is with 2 3/8 bypasses and an 87mm nozzle...it had the same pressure with 7/16 fittings but was a .1 faster with the 3/8's...no buck...90.7...


  2. #2

    Join Date
    May 2012
    Location
    California
    Posts
    1,790
    +1
    155
    Quote Originally Posted by OutlawGPR View Post
    I installed a gauge and fitting on my pump and tested to see what kind of pump pressure Im getting at 90mph. Currently running between 50-55 psi at wot...This is with 2 3/8 bypasses and an 87mm nozzle...it had the same pressure with 7/16 fittings but was a .1 faster with the 3/8's...no buck...90.7...
    so the big question is what psi is a problem

  3. #3
    Not really sure, I was hoping someone who has done this would know...

  4. #4
    1200Jet's Avatar
    Join Date
    Nov 2009
    Location
    Australia
    Posts
    164
    +1
    7
    This is my theory on the issue. I don't believe pressure has anything to do with it, although you should see a sharp rise in pressure as the relative angle of the impellers leading edge reverses.

    http://www.greenhulk.net/forums/showthread.php?t=246877

  5. #5
    GGG's Avatar
    Join Date
    Sep 2009
    Location
    Jersey Shore
    Posts
    2,831
    +1
    259
    Ive been told mid 60s max by a few people. I put a gauge and pressure reliefs in my polaris after the grate ripped off and almost tossed me. That ski would peak at 78psi. 75 trimmed neutral. I dont know what it was before the reliefs but I never had a problem with those number. Ive also read about being able to run high tunnel pressure with that sho as opposed to 4tec because of the added weight

  6. #6
    Steve-m31164's Avatar
    Join Date
    Jan 2013
    Location
    Melbourne Australia
    Posts
    2,787
    +1
    425
    Ive always thought it was mid 60s also ....in a gpr hull ... not sure on the other hulls ..

  7. #7
    gp1200rider's Avatar
    Join Date
    Mar 2008
    Location
    MD
    Posts
    1,010
    +1
    50
    Quote Originally Posted by OutlawGPR View Post
    I installed a gauge and fitting on my pump and tested to see what kind of pump pressure Im getting at 90mph. Currently running between 50-55 psi at wot...This is with 2 3/8 bypasses and an 87mm nozzle...it had the same pressure with 7/16 fittings but was a .1 faster with the 3/8's...no buck...90.7...
    Got a pic of your install on the pump pressure connection location ? Im about to do the same and drop this GPRXP in the water for the first time this season.

  8. #8
    I dont have a pic but it basically at the top of the 2 inch spacer at about 11 oclock. At twelve oclock there is rib and I did not remove it just moved over and drilled for a 1/4 inch pipe tap and put a hose barb fitting there. I drilled the hole at a angle to lay the fitting at an angle which provided more clearance for the hose to fit. I then screwed the fitting in and JB welded it to make sure it didnt leak around the thread because it is really thin. I then ground the fitting thread off with a die grinder to make it flush with the inside of the spacer.

  9. #9
    800AMSOIL4U's Avatar
    Join Date
    Aug 2006
    Location
    Morgan Hill, CA
    Posts
    5,025
    +1
    133
    Quote Originally Posted by OutlawGPR View Post
    I installed a gauge and fitting on my pump and tested to see what kind of pump pressure Im getting at 90mph. Currently running between 50-55 psi at wot...This is with 2 3/8 bypasses and an 87mm nozzle...it had the same pressure with 7/16 fittings but was a .1 faster with the 3/8's...no buck...90.7...
    What gauge set up are you using?


    Thanka

  10. #10
    fx160's Avatar
    Join Date
    Nov 2005
    Location
    gold coast australia
    Posts
    2,412
    +1
    194
    Quote Originally Posted by Steve-m31164 View Post
    Ive always thought it was mid 60s also ....in a gpr hull ... not sure on the other hulls ..
    That's what I have been told as well
    60 is about the safe limit

Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Diy pump tunnel reinforcement.
    By Pistonwash in forum Yamaha How To & FAQs
    Replies: 229
    Last Post: 11-29-2013, 12:13 PM
  2. Check your pump tunnels ...
    By Vern in forum 4-Tec Performance
    Replies: 18
    Last Post: 09-02-2008, 09:24 PM
  3. Pump tunnel reinforcement? JD1?
    By Vern in forum 4-Tec Performance
    Replies: 11
    Last Post: 01-30-2006, 05:34 PM
  4. PUMP TUNNEL REINFORCEMENT KIT
    By ABBOTT in forum Yamaha How To & FAQs
    Replies: 13
    Last Post: 01-08-2006, 11:41 AM
  5. Reinforcement of pump tunnel area around carbon ring
    By Green Hulk in forum 4-Tec Performance
    Replies: 12
    Last Post: 08-03-2005, 03:13 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
  •