Ummmm, Huh? maybe it's the beer, but why would you want to know a reading from there? 7 People read this and passed so I'll ask it.


Ray

Update: I guess I should clarify. You should read possibly flow there? or maybe vacuum? Not gonna get PSI from the suction side of the pump.

 This is a good topic.  I would like to tap my suction housing too.  I would think it would be better to tap it in 2 places (one high and one low) so you can try to balance the load on the impeller.   Anybody know the best places to do this ?

I have always wondered if I can Tap my "WJ" with a hose bib and hook the garden hose up to it and pump in water when running on the trailer. Of course it couldn't be the exact amount of water yo would get on the lake but i think it would help keep the WR lubed. Now this is all in theory.   

what my friend and i figured out when we would run his boat on the trailer was to hook 1 garden hose to the engine and disconnect the water feed line from the jet and hook another garden hose to that too so we would have water going thru the jet and engine, seemed to work fine.

OK, looks like the 1:00 and 5:00 placement is the place to be, so how far ahead of the impeller ?   I was thinking ( ), if there to close to the impeller it might give strange readings  . 

You mean behind the impeller? They are suction housing/intake readings. Not that some peeps don't take bowl pres. readings too.

No I meant in front of / ahead of the impeller, in the suction housing. I was thinking if it was to close to the impeller it might get some kind of weird readings (pulsing or swirling) as the impeller turned.

Maybe I'm confused, I was told to tap locations just before the wear ring. Wouldn't that be behind the impeller? Or maybe more even/level with the impeller? I've never taken a jet apart before, I'm just asking.

This is what I THINK - but it's just my opinion and WTFDIK, I'm not Dr. Phil or anything! 

Suction housing = inlet housing = gullet = big bent pipe where the water comes up and goes into the bowl.

From a standing start to full speed at WOT, the "pressure" inside the inlet housing will change from a slight vacuum to some amount of positive pressure. How much positive pressure will depend on the complex dynamics of each boat's hull, ride angle, impeller size blah blah. The reason it switches from slight vacuum to positive pressure as the hull picks up speed is because it isn't really a pump after the hull speed gets up around 30+ mph. It's some kind of weird hybrid of a pump + a no-bypass compressor. The inlet water isn't being sucked it's being rammed into the mouth of the impeller.

For the "average" boat that is under 60mph hull speed the maximum inlet pressure probably stays under 50psi - maybe way, way lower. For race boats the max pressure can be anywhere from 30 to 100-ish. I doubt there is even a consensus yet on what is good or bad value for pressure, but the race guys (or the ones who talk about it) seem to say that a successful boat will have a small amount of positive inlet pressure, but not too much. (Then again they could be handing out false info just like in a spy movie!)

There are various opinions on why you have to tap at two locations but on most boats, the pressure is not uniform at the impeller inlet. Some people think it is because of the "shadow" of the drive shaft blocking flow to the top of the inlet mouth. Others say it is because the water near the top of the inlet has a longer distance to flow than from the bottom. And there's the mysterious "boundary layer" which is the region of water near the surface of the hull which is flowing "past" the hull at less than full speed. So monitoring a single location will perhaps tell you the wrong story. If you are trying to use pressure info to "tune" loaders, shoes, ride plate, et cetera than you want to watch what is going on near the impeller mouth and at a "high" and "low" location.

I guess a better choice of words on my part would have been to said my taps are BEFORE the impeller, not behind. when Omar typed "in front of" ,and I reread your post "ahead of " it dawned on me we were on the same page. I'll see if I can put up a pic of my taps tonite. On a side note, the gauges stay remakably steady, they dont bounce aroud hardly at all. 1st time out this year I had my loader way too low(about 3/8" below) and my pres. was almost non existent, like 5-7 psi on top, and zero on the bottom. I trimmed it back to what I thought would be level(still about an 1/8" under). Now my #'s are like 22 psi on top, and about 10 on the bottom. Curious to see what others are seeing for lake/river boats. I read once where Timminator said 19 or so were good #'s for his 21 daytona. I'm going to shave the loader back a little more and see if that helps level it out.

Not my pump, but it shows the locations recommended by one of SoCal's premiere pump professionals. This is approx 1" ahead of the wear ring. If you go 2", you will have to move both taps a lot closer to the pump centerline, kind of working against the idea of a top and bottom pressure reading.

 Is that 3rd line for bowl pressure ?

Yes. This was a friend's dragboat and it was equipped with an Edelbrock QuikData unit.

Let's see if I can put up a short vid??

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