cavatation issues

« **on:** September 23, 2008, 02:24:11 PM »

i am experiencing this problem on my hole shot=have never had this issue before impeller change

southwind=460=500hp= setup before problem=stuffer/ droop/ride plate/loader grate/b impeller/5200 rpm==hole shot was great

bearing seized on pump shaft so i change out pump with a "A" impeller=5000rpm now have cavatation issue on hole shot

why would going from "B" to an "A" cause this=

rolling start i have no problem

« **Reply #1 on:** September 23, 2008, 02:51:15 PM »

Just a guess... With the A impeller you are probably getting a quicker blast when off plane. with the bow up it might be launching the intake out of the water from a dead start hence sucking air. You don't get the same thing when you're in a rolling start because your on plane and the bow is down launching you down river instead of skyward hence no air gulped down the intake.

« **Reply #2 on:** September 23, 2008, 06:21:44 PM »

It could be even more simple than that....the A impeller moves more water possibly causing more negative pressure in the intake, sounds like loader change time...

« **Reply #3 on:** September 23, 2008, 08:19:00 PM »

does that mean the race type loader or a whole nother design

one thing i did not mention that i did was at the exit end of the bowl i ground down all the vanes to a sharp edge=would that have an adverse affect

« **Reply #4 on:** September 23, 2008, 08:27:32 PM »

Quote from: just squirtin on September 23, 2008, 08:19:00 PM

does that mean the race type loader or a whole nother design

one thing i did not mention that i did was at the exit end of the bowl i ground down all the vanes to a sharp edge=would that have an adverse affect

You can getr pretty extreme on the stator vanes (bowl), I don't think I have ever heard of anyone having a cavitation issue due to bowl work, possible I guess. What type of loader are you running now? One of the super simple angle iron ones?, If its one of the straight ones and not one of the curved loader ramps that could be the issue, I dont think you need to go nuts...Do you have a standard rock stoppers you could try?

GT

« **Reply #5 on:** September 23, 2008, 08:38:56 PM »

one of the ss angle ones

still have the old grate to try

« **Reply #6 on:** September 23, 2008, 08:52:43 PM »

Quote from: just squirtin on September 23, 2008, 08:38:56 PM

one of the ss angle ones

still have the old grate to try

That experiment would be worth while...IMO

GT

« **Reply #7 on:** September 24, 2008, 09:35:45 AM »

Little bit more info needed. Are you running a stock wear ring or a bronze shouldered one? What is your axial clearance (i.e. clearance between the impeller wear ring skirt face and housing, or shoulder if shouldered wear ring)? What brand impeller? What brand was the last impeller and what were the clearances on the last impeller? Also, what brand is your loader?

« **Reply #8 on:** September 25, 2008, 09:10:23 PM »

cannot answer about those clearances as i put the pump on complete without looking inside

the old pump was not stock had some stuff done to it=all berkeley stuff massaged some=the new /used pump was a berkeley also stock aluminium impeller it seemed to be tight when i installed it

loader is an ss model from jbperformance which is rated to 500hp i believe

will be redoing the pump/w b impeller this winter and reinstall
will check all clearances when it gets removed

« **Reply #9 on:** September 26, 2008, 08:57:12 AM »

Doug call me when you get time for a chat on you "hole shot" issues Tom

(your scoop should arrive today) ! Tom

just squirtin

cavatation issues

wizard612

Re: cavatation issues

GT Jets

Re: cavatation issues

just squirtin

Re: cavatation issues

GT Jets

Re: cavatation issues

just squirtin

Re: cavatation issues

GT Jets

Re: cavatation issues

Jetaholic

Re: cavatation issues

just squirtin

Re: cavatation issues

jet boat performance

Re: cavatation issues