[Jetaholic]

On a Berkeley style (mixed flow) pump...

Is there an "optimum" ratio of bowl pressure to intake pressure (example, something such as 10:1 ratio with 300PSI bowl pressure and 30PSI intake pressure...numbers thrown out at random simply for example purposes)?

Is there an "optimum" AMOUNT of bowl pressure and an "optimum" amount of intake pressure? Example would be once the loader and shoe are balanced so that you're getting equal pressure at the top and bottom of the intake, is there an actual amount of pressure you shoot for?

Is it better to increase flow while keeping the bowl and intake pressures the same?

 

[[email protected]]

On a Berkeley style (mixed flow) pump...

Is there an "optimum" ratio of bowl pressure to intake pressure (example, something such as 10:1 ratio with 300PSI bowl pressure and 30PSI intake pressure...numbers thrown out at random simply for example purposes)?

Is there an "optimum" AMOUNT of bowl pressure and an "optimum" amount of intake pressure? Example would be once the loader and shoe are balanced so that you're getting equal pressure at the top and bottom of the intake, is there an actual amount of pressure you shoot for?

Is it better to increase flow while keeping the bowl and intake pressures the same?

Great Question... The Bigger the Varence the Faster the Pump or out put is the rule! But in the real world CHIT don't work like that..
Optimum would be 0-5 Intake pounds some wild bowl pressure Yet the way we load today is still not right... So the Best I Have seen was 3 fold:
Intake was 65
Bowl was 585
Nozzle Choke was 3.340 and it still holds the records.

 

[Boat 405]

Nozzle Choke was 3.340 and it still holds the records.

That's a huge nozzle.....

 

[76Miller]

That's a huge nozzle.....

Thank you......

 

[Jetaholic]

That's a huge nozzle.....

Thats what she said

 

[BLUE OVAL CP]

That's a huge nozzle.....

Thanks for noticing.... LMAO!! That was friggin classic!!

 

[bajadad]

This thread really got dicked around.....

 

[Boat 405]

This thread really got dicked around.....

Literally.

 

[GT Jets]

Great Question... The Bigger the Varence the Faster the Pump or out put is the rule! But in the real world CHIT don't work like that..
Optimum would be 0-5 Intake pounds some wild bowl pressure Yet the way we load today is still not right... So the Best I Have seen was 3 fold:
Intake was 65
Bowl was 585
Nozzle Choke was 3.340 and it still holds the records.

I like it!

Other than the later huge nozzle comments

Centrifigul type pumps are funny, if you really understood what's going on inside the pump I'm sure your mind would be blown...

You really aren't using 100% of the impeller to induce pressure resulting in flow, the faster the pump spins, the less efficient it becomes because of the centrifugal forces at work, the greater the intake pressure (within reason) the more efficient the impeller gets (talking mixed flow only here) because it's getting a "bigger bite".

There is a a lot of ways to improve the performance of the jet pump, I don't think we're even close to scratching the surface on the possibilities.

Anyways, the point I was trying to make, no matter the "ratio", I think you need to look at the setup as a whole, the less intake pressure you have, the harder the pump has to work to get the same outcome, too much pressure and all the work that goe out, gets taken from getting it in...

"Must learn balance Daniel son".

I have seen quite a few things done that look awsome on paper, but won't work in water....and vice versa.

Killer question BTWdevil

GT hand

 

[kojac]

Great Question... The Bigger the Varence the Faster the Pump or out put is the rule! But in the real world CHIT don't work like that..
Optimum would be 0-5 Intake pounds some wild bowl pressure Yet the way we load today is still not right... So the Best I Have seen was 3 fold:
Intake was 65
Bowl was 585
Nozzle Choke was 3.340 and it still holds the records.

Pops,
Do you know the choke or nozzle pressure in comparison to the bowl pressure?
I am assuming there is a loss due to water leakage around the turn pins and a pressure loss due to turns and cavities in the connections?

Thanks,
Kojac

 

[Jetaholic]

I like it!

Other than the later huge nozzle comments

Centrifigul type pumps are funny, if you really understood what's going on inside the pump I'm sure your mind would be blown...

You really aren't using 100% of the impeller to induce pressure resulting in flow, the faster the pump spins, the less efficient it becomes because of the centrifugal forces at work, the greater the intake pressure (within reason) the more efficient the impeller gets (talking mixed flow only here) because it's getting a "bigger bite".

There is a a lot of ways to improve the performance of the jet pump, I don't think we're even close to scratching the surface on the possibilities.

Anyways, the point I was trying to make, no matter the "ratio", I think you need to look at the setup as a whole, the less intake pressure you have, the harder the pump has to work to get the same outcome, too much pressure and all the work that goe out, gets taken from getting it in...

"Must learn balance Daniel son".

I have seen quite a few things done that look awsome on paper, but won't work in water....and vice versa.

Killer question BTWdevil

GT hand

Balance...that's pretty much where I was going with the "ratio" of bowl to intake pressure.

Now, I could be WAY off base on this, but in a comparison between two different pumps one would think that if one pump has a lower pressure differential between intake and bowl pressure than another pump (throwing random numbers out...say...pump "A" has 50 PSI of intake pressure for about 350PSI of bowl pressure) one would THINK that this would be a slight "overcharge" compared to say...pump "B" having 50PSI intake and 500PSI of bowl pressure. This would indicate that the impeller in pump "A" is flowing much less water than the one in pump "B", which would indicate that pump "A"'s impeller may not be the "optimum" match to the bowl and may require a smaller nozzle choke to bring the bowl pressure up.

Conversely, if you had say 50 PSI of intake and 600 PSI of bowl pressure, if you were trying to match the bowl pressure of pump "B" AND THE RESTRICTION WAS DUE TO NOZZLE SIZE one would think that you may want to run a larger nozzle to drop the bowl pressure down to increase flow.

Just throwing out a thought. Correct me if I'm thinking the wrong way on this.

 

[Sleeper CP]

Literally.

Figuratively

S CP bulb

 

[tahitijet]

I am by no means an expert nor do i really have any clue what i'm talking about but wouldn't you think that optimum would be the highest possible bowl preasure with the lowest possible intake preasure? wouldn't this mean that the impeller is processing the water at max effeciancy without overcharging

On a Berkeley style (mixed flow) pump...

Is there an "optimum" ratio of bowl pressure to intake pressure (example, something such as 10:1 ratio with 300PSI bowl pressure and 30PSI intake pressure...numbers thrown out at random simply for example purposes)?

Is there an "optimum" AMOUNT of bowl pressure and an "optimum" amount of intake pressure? Example would be once the loader and shoe are balanced so that you're getting equal pressure at the top and bottom of the intake, is there an actual amount of pressure you shoot for?

Is it better to increase flow while keeping the bowl and intake pressures the same?

 

[Doc Nozzle]

I am by no means an expert nor do i really have any clue what i'm talking about but wouldn't you think that optimum would be the highest possible bowl preasure with the lowest possible intake preasure? wouldn't this mean that the impeller is processing the water at max effeciancy without overcharging

Yes, the difference between bowl static and inlet static is telling you how much pressure the impeller design (and bowl/wear ring clearances) are achieving. An increase of 5psi at the inlet will raise the observed bowl static by that same 5psi, so you have to look at "delta P" (pressure rise across the impeller).

So OK, say you have some hardware with high pressure rise - that's a good start! Now, what flow rate is occurring and how much is the flow being accelerated?

High flow at high choke = good thrust
Low flow low choke = bad
2 boats with same flow, same choke. 1 has a higher pressure rise (bowl - inlet). That boat needs more engine power than the other to move the same flow of water.
Which boat goes faster? Whichever one has the better hull/trim/rigging combo to take advantage of the developed thrust.

2 boats with same max bowl pressure number (without knowing inlet pressure, impeller size or bowl/nozz choke info). Which is better boat? Doesn't mean jack.

 

[Circular]

wouldn't this mean that the impeller is processing the water at max effeciancy without overcharging

Please explain what overcharging means.

Circ

 

[tahitijet]

Please explain what overcharging means.

Circ

what i meant by overcharging was when you get substantialy more water into the intake then the pump can process.

hence the reason i was thinking that the lower the intake psi with the highest bowl psi was correct. once the outlet psi stops climbing if the inlet preasure keeps going up your just craming more water in front of the impeller then it can process.

agian I really have no clue what i'm talking about this just makes sense to me as i sit here and think about it.

 

[tahitijet]

btw,, way off topic here but is doc nozzle by any chance lvjetboy from the last board??

 

[Doc Nozzle]

btw,, way off topic here but is doc nozzle by any chance lvjetboy from the last board??

Nope, and at the time of my 1st post I didn't know who he was. But one of the readers (from here at PB) clued me in and I went to the HB archives and now I sort of understand why you ask.

Whether that's good or bad I don't know. I got tired real quick reading all the BS from both directions so I'm not sure what really went on there.

For those of you who "interacted" with him on HB, I'm a different guy.

And since I am not a racer, I will now return you to our regularly scheduled thread.

 

[tahitijet]

i didn't mean the referance in any sort of bad way. just that he was also very technical and very imformative. even though there was drama, most people would agree his post were a good read as are yours. by all means keep posting.

 

[bp298]

what i meant by overcharging was when you get substantialy more water into the intake then the pump can process..

that's a very accurate description. overcharging, or "blowing the tail". suction pressure rises to such a level that the impeller cannot create a pressure differential, bowl pressure (flow at any velocity) drops like a rock while inlet pressure is rising, the boat has no forward momentum and falls on it's face. it can be an interesting ride...

hence the reason i was thinking that the lower the intake psi with the highest bowl psi was correct. once the outlet psi stops climbing if the inlet preasure keeps going up your just craming more water in front of the impeller then it can process..

if you look at a data file from just about any boat, you'll see that suction pressure is never "static"; it doesn't just climb to a pressure point and draw a straight line. suction pressure oscillates. some boat's data indicates significant oscillation, some not so significant. of course, people can set sampling rates so far apart that this oscillation is severely dampened, but then it doesn't really demonstrate what's happening, or when it's happening.
all of the programs provide methods to obtain a mean average, plus high and low for a given parameter, which is useful.

bowl pressure also oscillates, does not rise to a point and draw a straight line.

generally speaking (almost all the time), bowl pressure oscillations DO NOT follow suction pressure oscillations. i.e., suction pressure dropping 3-5 psi does not result in a corresponding bowl pressure drop of 3-5 psi. they are independent of one another.
however, if i see a decline in suction pressure to a certain point, they will be oscillating together, and i'll see an overall decline in bowl pressure. not massive, but enough to have a reduction in forward momentum. there are a number of things that can lead to this - most related to setup, but water conditions also play a part.

i like to see a mean average suction pressure between 15-30psi above the point suction pressure oscillations affect bowl pressure. suction pressure can be anywhere in that range, bowl pressure will remain close to the same mean average.

this stuff won't be seen using gauges - they are dampened, and they don't respond quickly enough. disecting a datafile after a run provides a lot of insight.

An increase of 5psi at the inlet will raise the observed bowl static by that same 5psi, so you have to look at "delta P" (pressure rise across the impeller)...

true for multi-stage centrifugal pumps, not true in a single stage centrifugal pump. i can increase suction pressure 10-20 psi, and not see any more than a 5 psi, or less, bowl pressure variation.