Has anybody or any group of jet boaters for that matter. Recorded intake pressures and relative bowl pressures. I was wondering if there was any insight to be gained by this. I realize it is probably a per hull/pump combo kind of thing. but it seems that there should be some knowlege or troubleshooting info from it. for instance you change nozzles from 3" to 3 1/4" wouldnt your intake pressure stay the same and your bowl pressure be less at the same RPM. Then what would the result be in terms of holeshot and top end? Im just trying to get a feel on what people out there have found. even though I dont have a high end pump. (mine's a Panther) Im always looking for little things for improvement. With my stock exit housing I have no cavitation and a great holeshot. My motor turns the pump 5400 to 5500 RPM at about 58 mph. When I swapped with the Panthervator one I have, Its like a slipping clutch. Theres no way I can floor it out of the hole, unless I wish to rev my motor passed 6200 RPM. with nothing else changed, other then the exit housing.
  So I tapped a couple 1/8" inch holes, one in the suction housing area, and one in both exit housings in the same place. The rear ones are just above a stator vane, as thats where the cooling system pick up is located as well (just above a different vane) I figure thats probably the highest, high pressure area. heres a couple pics.



After I go get a little data, maybe then I can figure out whats going on. anyones previous pressure findings would ne great to hear.

There are several posts like this on PB and maybe some from SCJB if you do a search. Generally, the poster is asking what readings he should be getting and/or where on the intake to make the taps. The gist of the replies is:
a) tap the inlet in two locations (near the top and near the bottom)
b) always to try and get the readings as uniform as possible across the eye of the impeller. But it doesn't read to me like anybody ever gets them totally uniform, but that the boat does better once a loader is tuned to get them close.

Then a debate ensues about which are the two best locations - especially the top tap. Seems like most people say that if the tap is at the very top 12 o-clock it will get a lot of "shaft shadow" and turbulence.

The other common response is that little or no pressure in the intake is bad and real high pressure is bad. IIRC the "better" values are maybe in the 10's - 30's psi.

Bowl press taps seem to only need one location.

And whatever average pressure you are getting at the intake is "carried" into the bowl pressure value. If your observed inlet pressure goes up by 20psi then your observed bowl pressure will go up 20. Therefore (IMO) it isn't what the bowl pressure gage reads that matters but what the delta P difference between bowl static pressure and inlet static pressure is. Bowl press minus inlet press is an indication of what performance your impeller is achieving.

There are other members who will know much more than I do however!

Thanks SteveCat! I did a search here and didn't really find what I was looking for. I think you answered what I wanted to know. Besides me being the curious/experimental type. I had hoped someone had made a few conclusions about the pressure differentials. At least now, besides just recording my findings, I can make some kind of usefull assumptions from the pressures I get. Thanks again for the info. Oh, BTW I remember the old addage about assuming.....so.......(trying to duck the snide comments) S. Mac

Gotcha, that makes good sense. Since the addition of the Panervator. I have developed a bit of cavitation right out of the hole. It does not Cavitate with my stock exit housing in Place. Thus the need to see what is going on pressure wise. Heres a short clip on the trim Im getting out of the nozzle since I cleaned up Panthers Mediocre Machine work.