Laid Back Boaters

Well do to my almost "Chuck Norris" like ability to visualy analyze mechanical devices! I think I have found a difference between an Exit housing that "Cavitates when Hit hard out of the Hole, and one that "Does Not" In an "Axial Flow style Pump, what should the distance from impeller vanes to the stator vanes be? The reason I ask is.....the stator vanes are 3MM farther away from the impeller on the exit housing that cavitates. here's the comparison.



What you guys think, that difference cause it to Cav?

Did you guys hear that Chuck Norris jumped into a pool and didn't get wet.... the water got Chuck Norrised


Now on to more serious matters. I would think that if you make a gasket that was an additional 3mm and put it on the non-cavitaing exit housing and try it that would tell you if the 3mm is the difference or if something else is your culprit. If for some reason that fixes it you can take 3mm off the mounting face of the cavitating one.

I've heard that "Cats have Chuck Norris like reflexes!"



Except I dont have a mill, and it is more than one surface, outside flange, outside lip, stator face, stator ring height, DU bushing and seal Height. I was thinking of tig welding a bead on the stator vanes, and reprofile the leading edge!

In the first part of this video, you can hear me pedal the throttle a bit to try and limit the RPM's. You hear the amount of slip I'm getting. Very Annoying.

very interesting! I agree with kona on the gasket thing would give you and answer.....thinking as I type and in doing so, it may not give the proper answer. The reason being is putting a thick gasket in there will move the stator ring further back also which can and probably will cause the efficiency to go down. Hmmmmm

My thoughts exactly. For the Helluvit, I sent Steve@Panther Jet an email, mentioning that I had aquired another Panther Jet. and see what the spec is between impeller edge and stator blade. we'll see if he answers

Oh yeah, since I had the tail off anyways, I tapped all of the vent holes in the stator vanes to be able to plug them easily to see what that does. I even picked up 8 set ss screws to do it.

damn, lots of holes! Why don't you just leave the top 4 holes unplugged so when you run down the river you'll look like a peacock

ROFL!! all 8 of em are in the bottom, or I prolly would have tried it by now!

Steve, How are you...... I would slow down a bit before you start blocking off those vent holes, they are there for a reason. The stator seal mates with the rear face of the impeller to relieve the pressure on the rear of the impeller and reduce the thrust load on the shaft tail bearings. Leakage in this area is vented by these holes. A tight fit should be maintained between the impeller and stator seal. This is controlled by shimming washers ahead of the impeller. This is the axial clearance, it should be .020 to .030. To check the axial clearance you lay a straight edge across the rear face of the pump housing with the impeller on the shaft and measure the gap with a feeler gauge.
The radial clearance is the distance between the ridges of the stator seal and the inside of the impeller hub. This should be .015. If your stator seal ridges are worn you will loose alot of efficiency here. Hole shot cavitation won't come from the vent holes. You have other issues. Jim

Thanks Jim for posting. I was hoping you and/or Tom would jump in. with a straight edge, impeller clearance is .020", the stator rings are even in better shape on the tail housing with the Panthervator then in my exit housing. yet I see no cavitation with my exit installed. The only 2 physical differences I could find were the distance to the stator blades from the impeller & the size of the exit. This is a sleeved pump and all the other pump specs are well within the numbers. just trying to figure out where the variable is between the 2 exits thats causing the cavitation.

Steve, Interesting, your regular housing cavitates less, now I see where you are coming from.... I don't have an answer...... I hate that..... Jim

I read a little further back that you also use a gasket between the 2 housings?? I can say I only feel cavatation at high speed with rough water but mine does not have a gasket I use black silicone sealer between the 2 housings plus I have the 4" FINS on the trim plate. I do know not having the gasket will make the impeller closer to the stator housing and the fins help the handleing these are the only changes that have been done to mine.

Kriss, I DO NOT have a gasket between the pump and rear housing. That was a possible suggestion to see if my original exit would cavitate like the Panthervator one does. I have the 2" deep fins on my ride plate, which I like better then the smooth one I had before. I went ahead and welded a piece of 1/8" Stainless on each side of my Panthervator nozzle to make the exit size the same as my original. (which does NOT cavitate) so next time out I'll see if that makes any difference. If not, the only other difference between the 2 exit housings is the distance from the back of the impeller to the stator vanes. So after next test I may weld a couple of beads on to each vane, reprofile them and see if thats possibly where the problem is. From what I've read, and everyone I have talked to, no one seems to think that the difference in the stator vanes would cause cavitation. but I wont know unless I try it.

A little more info for the record. To quote the E-Mail I received from Panther Today:

"Try measuring the exit section first.
You must have calipers or something very accurate.
There are many different size
Exit sections for different horsepowers.
Compare the dimensions to your
Non-cavitating stater.
Also take a 3\8 drill bit and make sure the vent holes are open.

If this does not help let us know."

Interesting! First off this bit- There are many different size Exit sections for different horsepowers.
I was not aware of MANY different size exit housings for different power levels!

Secondly- Also take a 3\8 drill bit and make sure the vent holes are open.
My Stater Vent holes are only drilled 13/64" (just bigger then 3/16") on both exit housings. OK, off to find where my digi brake drum caliper is hiding.