SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: speedymopars on October 02, 2010, 09:56:12 AM
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Ok everyone says AT's are better and they load the pump harder. They certainly look better BUT does it make the boat go any faster? Basically the load on the pump is the water flow and resistance, and one that loads harder well, doesn't that just mean it is flowing the same at a lower RPM?
If I took two impellers, say an A3 Berk and an A2 AT, and they load at the same RPM, will one actually be faster?
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Welcome back Speedy, long time no see. Did you crack an impeller with that mighty Mopar ?
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Speedy withstanding, some visual and finish quality differences nearly all the production impellers availble are going to act and react the pretty much the same , the differences in exit blade angle and in some cases blade dimensions vary slightly the big difference over the past years is the Older Agressor cuts which were numbered (letter designated) "off" the industry standard ( eg thier "A" was closer to a Berk "AA") This BTW does not apply to non energized Jacuzzi Tom
Heres a brand new un-detailed AT/Dom aluminum
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2F09misc%2FDSC04326.jpg&hash=a0be2a2f5aed00b30a2e93569f99541fb56fd47e)
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Welcome back Speedy, long time no see. Did you crack an impeller with that mighty Mopar ?
Nope, but I'm goin' big with a 543ci Mopar. I figured I'd take advantage of the 675ft/lbs at 3k :-)
Happy to be back :-)
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Speedy withstanding, some visual and finish quality differences nearly all the production impellers availble are going to act and react the pretty much the same , the differences in exit blade angle and in some cases blade dimensions vary slightly the big difference over the past years is the Older Agressor cuts which were numbered (letter designated) "off" the industry standard ( eg thier "A" was closer to a Berk "AA") This BTW does not apply to non energized Jacuzzi Tom
Heres a brand new un-detailed AT/Dom aluminum
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2F09misc%2FDSC04326.jpg&hash=a0be2a2f5aed00b30a2e93569f99541fb56fd47e)
So if I'm reading you right, 500Hp loading = X GPM regardless of RPM.
If I'm not trying to get every last MPH out of something, then really just having the jet clearanced right matters more than if I get an AT or Berk impeller. Right?
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So if I'm reading you right, 500Hp loading = X GPM regardless of RPM.
If I'm not trying to get every last MPH out of something, then really just having the jet clearanced right matters more than if I get an AT or Berk impeller. Right?
Speedy I have no GPM numbers or references for them but Berk type Jet drive/impellers are very pathalogical , X HP will turn X impeller cut X RPMs , (assuming all is/are working properly) So 500 hp will turn just about anyones "A" (except Aggressor or Jacuzzi ) @ 5k + or - . Heres an extended HP chart that might be of help Have some other info I'll post up from the late Jac Sea that might be of help Tom
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2Fimpeller_Chart1.jpg&hash=b6cb5ef94f1b19b5713fa0e872ef5ae632c375bd)
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Just to add to this... :D
GPM numbers are 100% irrelevant......Let me explain myself....
The amount of flow will dramatically increase and decrease with the amount of horsepower involved. That goes without saying.
But.... :) The GPM does not really come into play, nor is it easy to measure. The GPM does not move the boat forward. The thrust does...Measured in volume AND velocity, to get there you need pressure. ;) As the pressure goes up, it is accepted that the flow (GPM) can go down absorbing less horsepower (sounds backwards, but it isn't) . :sly:
So the true balance is when you can make peak thrust at peak HP, it is virtually impossible to get it right the first time no matter how hard you try....
Another really warped way to look at this is think about the material taking up space inside the pump....A common thought (which I totally agree with BTW) is that the thinner the impeller and stator vanes are, the more room there is for water, thus the more potential for improved performance.....The fuzzy math comes in when figuring how hard that water is to start and stop the rotational forces and generate axial thrust (think about it) the more water you flow, the more HP you eat up just changing it's direction. :mad:
I am from the old school train of thought....Make it smooth, skinny, and strong, then balance it to the gnats ass and it will do everything that is asked of it, but it still has to be cut to get the engine to spin it's desired RPM, otherwise it all goes out the window... :-\
BTW, the term loads better is a farce, I use "stays loaded better", this is due to having less lift built into it, but a better shaped blade/vane...I have done some serious research on this, but never had the scratch to put it into play...
The determination of "faster" is a farce too....just because you can increase the exit velocity, does not mean more speed, sometimes quite the opposite, the volume has to back it up...Without balance, you got squat.... :D
Remember, water is mass, bigger is not always better, but more is always more... ::) ;D
GT
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Just to add to this... :D
GPM numbers are 100% irrelevant......Let me explain myself....
The amount of flow will dramatically increase and decrease with the amount of horsepower involved. That goes without saying.
But.... :) The GPM does not really come into play, nor is it easy to measure. The GPM does not move the boat forward. The thrust does...Measured in volume AND velocity, to get there you need pressure. ;) As the pressure goes up, it is accepted that the flow (GPM) can go down absorbing less horsepower (sounds backwards, but it isn't) . :sly:
So the true balance is when you can make peak thrust at peak HP, it is virtually impossible to get it right the first time no matter how hard you try....
Another really warped way to look at this is think about the material taking up space inside the pump....A common thought (which I totally agree with BTW) is that the thinner the impeller and stator vanes are, the more room there is for water, thus the more potential for improved performance.....The fuzzy math comes in when figuring how hard that water is to start and stop the rotational forces and generate axial thrust (think about it) the more water you flow, the more HP you eat up just changing it's direction. :mad:
I am from the old school train of thought....Make it smooth, skinny, and strong, then balance it to the gnats ass and it will do everything that is asked of it, but it still has to be cut to get the engine to spin it's desired RPM, otherwise it all goes out the window... :-\
BTW, the term loads better is a farce, I use "stays loaded better", this is due to having less lift built into it, but a better shaped blade/vane...I have done some serious research on this, but never had the scratch to put it into play...
The determination of "faster" is a farce too....just because you can increase the exit velocity, does not mean more speed, sometimes quite the opposite, the volume has to back it up...Without balance, you got squat.... :D
Remember, water is mass, bigger is not always better, but more is always more... ::) ;D
GT
Glenn
Thanks Glenn ,but I think I just poppped a blood vessel in my head ;) Tom
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Glenn
I know, my wife already said I have a problem.... :screwy:
GT
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I know, my wife already said I have a problem.... :screwy:
GT
F'n A Cotton F'n A
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Nope, but I'm goin' big with a 543ci Mopar. I figured I'd take advantage of the 675ft/lbs at 3k :-)
Happy to be back :-)
Just go to a AA or AAA , and use that torque :thumbup:
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Aggressor took one look at it and said Big Block Mopar? Go A3 and spin it to 6K easily.
Ok, maybe the last part I made up . O0
Actually, they took a look at the curve and said I should use thier Bronze A3.