SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: Stevecat on August 26, 2008, 08:17:18 PM
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Does such a thing exist? I'm talkin about a rig in somebody's shop that can run any make jet pump at any combination of RPM, inlet angle and inlet water velocity and tell you stuff like thrust, GPM, output water velocity or whatever.
If it does exist I want to see it! If it doesn't exist then maybe I should build one..... 8)
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Were workin on it ;D ;D ;D
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2Fth_MOV00096.jpg&hash=562edf23085e4c7b246b912520ae260962b0b044) (http://s147.photobucket.com/albums/r319/jetboatperformance/?action=view¤t=MOV00096.flv)
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What did we learn from this video?
That Jacuzzi WJ pumps work well on lathes :D
I've heard of a shop that had a back in style pool that you could run the boat on the trailer, but I don't think they had any data collection system.
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Tom could combine a margarita mixer/ l o n g distance dispenser!!! :D
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Tom , You should know better than to run those things dry :screwy: ;D
-beerjet-
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Omar It had an A$$ load of lube on the W/R O0 , Crew no lesson ,that was a "joke" of sorts , that WJ jet was sent rebuilt to a guy in North Carolina who had IMO 0 mechanical skills , we paid to ship it back here after he told us it "vibrated" uncontrollably at 1500 rpms ,turned out he had had his D/L "overhauled" and its was masively off and he had rotten stringers and Mad motor mount Sag causing the "Dog leg" in the DL as well after that demo he cheerfully paid to have it shipped back Tom
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Hey Stevecat! have you given up on this idea?, I was working on some stuff today that gave me a couple of really good possibilities.
I was working on a swimming pool pump today (25 HP three olympic size pools) and had installed a VFD (variable frequency drive) which is a speed control for three phase motors, anyways, while ramping this pump up and down, I could tell by some simple math calculations exactly how much horsepower was being used and came up with a definate curve on the pump that came remarkably close to the curve supplied by the pumpmaker.
My thoughts are to build a pump dyno using an electric motor with a speed drive on it, you will be able to tell the horsepower used and torque required and rpm on every possible scenario, it would be expensive though, you would need a 500 HP electric motor and a 500 HP VFD and the electrical power to run it, but could be done...The problem is I don't think you could dyno enough jetpumps to pay for it.... :-\
A while back (several years ago) I was breaking in an engine on the lake tied to a dock, I was kneeling alongside the engine running the throttle by hand on the carb. and was not really paying attention to my surroundings, I looked up and me, the boat and the dock I was tied to was about 100 Yards off shore (whoops), so what ever you tie the boat to, make sure its up to the task... ::)
BTW, my dyno is my ass in the seat at the lake with a GPS and a vacuum guage ;D
GT
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A while back (several years ago) I was breaking in an engine on the lake tied to a dock, I was kneeling alongside the engine running the throttle by hand on the carb. and was not really paying attention to my surroundings, I looked up and me, the boat and the dock I was tied to was about 100 Yards off shore (whoops), so what ever you tie the boat to, make sure its up to the task... ::)
GT
Now thats funny ;D ;D
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A pump dyno currently is a waist of time. The video could very easilly show a pump with massive clearences but with a nice weight balance. We did a dynamic balance like that thirty five years ago. Not much to gain. What you don't know is how well each individual blade of the impeller matches the others. Is the bite exactly equal, is the front side and back side cup exactly equal, are the blade cords equal, any of these things will scew up the ballace when loaded. Then you throw in the dynamics of water flow through the pump in a moving boat and there are more variables than can not be computed at this time. Issues like how much cavitation comes off the loader, or even the bolts of the loader? does water break off the gap between the suction piece and the impeller? Is there cavitation on the back side of the loader ramps? Is there any problem with the shoe, too deep, too shallow? Lord knows what problems an inducer could create with flow while increasing the intake preshure on the front of the impeler. God the variables haven't barley been touched in jet design. If you wanted to develop a dyno for a pump I guess it would take preshure indicaters, slo-mo cameras, and an 800 hp electric motor. Then mount the pump upside down under a large swimming pool and then you could get an idea of what goes on after the intake, that's all. Gooood luck!
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A pump dyno currently is a waist of time. The video could very easilly show a pump with massive clearences but with a nice weight balance. We did a dynamic balance like that thirty five years ago. Not much to gain. What you don't know is how well each individual blade of the impeller matches the others. Is the bite exactly equal, is the front side and back side cup exactly equal, are the blade cords equal, any of these things will scew up the ballace when loaded. Then you throw in the dynamics of water flow through the pump in a moving boat and there are more variables than can not be computed at this time. Issues like how much cavitation comes off the loader, or even the bolts of the loader? does water break off the gap between the suction piece and the impeller? Is there cavitation on the back side of the loader ramps? Is there any problem with the shoe, too deep, too shallow? Lord knows what problems an inducer could create with flow while increasing the intake preshure on the front of the impeler. God the variables haven't barley been touched in jet design. If you wanted to develop a dyno for a pump I guess it would take preshure indicaters, slo-mo cameras, and an 800 hp electric motor. Then mount the pump upside down under a large swimming pool and then you could get an idea of what goes on after the intake, that's all. Gooood luck!
Hey Stevecat, I think we're on to something here ::) There seems to be a common denominator, guess I better keep my eyes open for a good used motor and VFD??????
GT
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OK I have been thinging about it and I think the only way to get some kind of idea on how your pump is working is to get some data on the lake. Get RPM / intake preshure, GPS / RPM, Nozzel Velocity / Manifold preshure, I don't know, then take the engine out and run it on a dyno and try to recreate the runs on the water. This would give you an idea of the pump efficiency at different points allong the engine's power curve and might tell you when it drops off due to internal problems. Then swap pumps and do the same thing noting all the similarities and differences between the pumps. Have a few beers and figure out why one is better or worse than the other. It will probably come down to water conditions or the quality of the beer. Or it might figure out a way for a jet boat to break the sound barrier with 150 horses, who knows.
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Hey wizard, I think there would be some value to some real world data, but think what that data could mean if you had two pumps that had been dyno tuned to some extremes....you could literally build an engine that could take full advantage of the information gotten by the pump testing, I'm not saying it would be cost effective, especially at first, but with more data comes more questions, as of late, most of the OE's have basically cookie cuttered the hell out of everything, may be some magic to be had, maybe not...The reason I am curious is the new High Helix impellers, bet someone wants to nail that thing on the head...
Sometimes a very small change makes an enormous difference in the world of pumps, wouldn't it be cool to know why?
These types of questions and throwing rediculous ideas around is how major breakthroughs are made IMHO...
I'm working on a couple of super silly things right now that are a couple years old, and are just now starting to blow my own mind... I'm very close to something that could change the world on a small scale...
GT
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I remeber back in the day we talked to Phil Trishler and the guys who originally designed the Berkley. They seemed to be beyond rocket scientist. After only a couple of years we started to massage whet they were producing and made big gains. First was the loader. Steve King welded the first one up in high school metal shop. We built what seemed like hundreds of them to see what worked best. Most of those designs I still see today. We grinded, smoothed, balanced, filled, reduced, expanded, raised, lowered, you name it. Now every one "knows" what to do. They install and tweek it seems. Nothing radical. If you have some out there ideas, go for it. First time we ran a loader people thought we must have been running fuel, nope just a radical idea.
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I made a nozzle a few years back (closer to ten) that made a Spectra 20 plane like an I/O, but couldn't get the reverse gate to work right, it didn't effect top end hardly at all (still went 59 MPH but at 150 lower RPM)...I think there are a lot of advances out there that haven't been discovered yet, could be totally full of crap, but I think the jet still has a lot of unleashed potential that may even equal the stern drive, if not very very close, it's like my grandfather said once, it's so damn simple, it's stupid...Don't have to be. He always wanted to play around and build a positive displacement pump, but at 80 years old, just couldn't do it, I have his notes and seems doable, just need some time and some money..........Welcome to my world. :'( Wah.
BTW, still have my prototype nozzle, but the boat has been sold....No, I will not post pics ;)
GT
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The Berk guys were probably gods for their day. They had to do shit the hard way. By pencil, paper, intuition and then a lot of prototype work makin chips. But they could not have got it all right. Like Wiz says, there are too many variables. Like most of us, I think I know enough to be dangerous. And when I look at an impeller and see straight leading edges and relatively simple "airfoil" shapes, I'm pretty sure there's more to be had. Just look at a Hamilton impeller.
http://www.hamiltonjet.co.nz/includes/files_cms/file/JetTorque%2011.pdf (http://www.hamiltonjet.co.nz/includes/files_cms/file/JetTorque%2011.pdf) (and go to page 2)
Much more complex shape. They are probably the only OEM to do modern computer analysis of a pump system. But they don't seem to be into racing...
And look at anything designed in the 60's compared with it's modern counterpart. Airframes, jet engines, auto engines, bridges, buildings. It's all changed. Anyways, maybe there are some improvements to be had and maybe not. But a dyno with accurate measurements and repeatable results would go a long way to helping rig a boat properly.
And like GT says, there are two things a jet dyno could do: 1) allow you to either match the pump exactly to the motor you built, or the other way. 2) maybe after running several makes/models of pump with all the various tricks and shit we do today, we might discover that there are some more tricks lying around. I suspect that's how fuel injection got adopted, or blowers, turbos, blah blah.
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Hey Stevecat, I think we're on to something here ::) There seems to be a common denominator, guess I better keep my eyes open for a good used motor and VFD??????
GT
Yeah find us a cheap 500HP with VFD, then about 800 ft^2 facility with a BIG main breaker panel, good water and a floor drain. And I think we need a 2.5:1 speed increaser with good quality gears. :o
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OK I have been thinging about it and I think the only way to get some kind of idea on how your pump is working is to get some data on the lake. Get RPM / intake preshure, GPS / RPM, Nozzel Velocity / Manifold preshure, I don't know, then take the engine out and run it on a dyno and try to recreate the runs on the water. This would give you an idea of the pump efficiency at different points allong the engine's power curve and might tell you when it drops off due to internal problems. Then swap pumps and do the same thing noting all the similarities and differences between the pumps. Have a few beers and figure out why one is better or worse than the other. It will probably come down to water conditions or the quality of the beer. Or it might figure out a way for a jet boat to break the sound barrier with 150 horses, who knows.
An alternate way is to have a big HP motor with VFD. First you spin your jet dyno through 0-5000rpm without any load and jot down motor amp draw vs shaft speed. This will give you no-load power consumption.
Then you bolt on your jet pump unit to this imaginary dyno rig. Pump is just out to the bowl, no diverters or steering shit. This discharges into a sensor pipe. All you really need is two pressure ports on either side of a slight orifice. From those two pressure readings you can get a lot of shit. You could also have a pitot tube or two just for fun. What you want is to calc hydraulic power of the jet exhaust. With these two points of info - input HP (at the shaft) and jet hydraulic power you can figure out pump efficiency. I bet it's actually quite shitty. Probably around 85%. From there you play and make changes. You don't need flow viz even though it would be fun to have everything clear just to watch the fish swim by. But the end goal is just to make changes that increase pump efficiency. It's all about max mass flow per input HP. The amperage measurement can be very accurate so it will detect slight changes in pump performance.
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Yeah find us a cheap 500HP with VFD, then about 800 ft^2 facility with a BIG main breaker panel, good water and a floor drain. And I think we need a 2.5:1 speed increaser with good quality gears. :o
Gotcha covered there, I have Andrew Casale's buisness card in my wallet (Casale Engineering) ;)
GT
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It seems like the Engineers, Designer, R and D departmets of said manufacture of pump would have to have such a device to collect data or improve on a product. Or at lest something similar to what you guys are thinking of shouldn't they? Not that thay would ever tell you how to make one.
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I now have "dozens" of pages of Impeller dyno results for AT/Dom aluminum ,stainless, 9.5 and Hi helix Impellers These are "oberved and "corrected - 3%" and I will post them individually for anyone that wants to provide a "Scenario" I havent been given permission to release them as a "chart" nor are they in that form yet Tom
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I've talked to Duane a little about the HH, and it sounds like my berk bowl would have to be modified for one. Just curious if I bought a new AT bowl, would the HH be "a bolt in"???
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Yes but I will "leak this" even though the HH works Bitchen it works "Better" when we (or Duane or Jack) "rework it" a smidge ;)
ps I would sell you an Dominator Bowl vs AT or my C conversion (strength factor ,same price or less ) Tom
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It seems like the Engineers, Designer, R and D departmets of said manufacture of pump would have to have such a device to collect data or improve on a product. Or at lest something similar to what you guys are thinking of shouldn't they? Not that thay would ever tell you how to make one.
I called 10 places around the US and even called the US office of Hamilton. They all said they don't have a pump dyno. American Turbine has an impeller dyno. So they can tell you how much shaft power an impeller absorbs - which is very important of course... but it is not the same as inside a bowl and with water getting sucked, rammed and who knows what else up the intake, through the impeller across the wear ring over the stator vanes down the throat and blah blah.
Now I may have been getting sandbagged by some of them that I called but I tend to think not. A real pump dyno that could properly deal with the flow rates of a pump and then recondition the water and get the air out of it and back into the inlet at simulated hull speeds of 100mph would be big, expensive and very tedious to operate. And we would have heard about it. There are of course some very large and fast water tunnels in the US. But these are usually academic/government operated and not rigged to do jetboat pumps all day long.
Jack at MPD told me what he was told of the story of how the Berk company developed their pump and they most certainly did NOT have much in the way of test equipment. They were doing what we do now - use the assmometer.
So the most fascinating thing for me about all this is that it would appear that nobody really knows whether a jetboat pump is 50% efficient, 75% efficient or 99% efficient (at converting engine shaft hp into thrust hp).
PS - I've got $1 that says they are not 99% efficient! ;)
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I called 10 places around the US and even called the US office of Hamilton. They all said they don't have a pump dyno. American Turbine has an impeller dyno. So they can tell you how much shaft power an impeller absorbs - which is very important of course... but it is not the same as inside a bowl and with water getting sucked, rammed and who knows what else up the intake, through the impeller across the wear ring over the stator vanes down the throat and blah blah.
Now I may have been getting sandbagged by some of them that I called but I tend to think not. A real pump dyno that could properly deal with the flow rates of a pump and then recondition the water and get the air out of it and back into the inlet at simulated hull speeds of 100mph would be big, expensive and very tedious to operate. And we would have heard about it. There are of course some very large and fast water tunnels in the US. But these are usually academic/government operated and not rigged to do jetboat pumps all day long.
Jack at MPD told me what he was told of the story of how the Berk company developed their pump and they most certainly did NOT have much in the way of test equipment. They were doing what we do now - use the assmometer.
So the most fascinating thing for me about all this is that it would appear that nobody really knows whether a jetboat pump is 50% efficient, 75% efficient or 99% efficient (at converting engine shaft hp into thrust hp).
PS - I've got $1 that says they are not 99% efficient! ;)
Several years ago when the outboard co's started using kilowatts as a horsepower indicator, we figured the efficiency of a prop to be about 87% on average, after playing around with the numbers, we came up with a good running jet to be somewhere in the nieghborhood of 60% based on performance indicators of accelleration, speed and rpm. Seems real to me...
A horrible comparison would be the old Berkeley outboard jet lowers, if you took the prop gearcase off and installed a jet lower (same boat) the boat would lose about 30-40% of its top speed and take twice as long to plane out but turn a buttload more RPM...Sort of makes total sense again...
GT
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The "Impeller" dyno should not be discounted IMO, the HH (and other)Impeller readings were only very slightly of the actual Engine dyno readings in the test boats Tom