How much GPM

[SeaSlut]

How much GPM does a stock Berkely pump A impeller Flow at say 2000 RPM, 300 RPM, 4000 RPM, 5000 RPM.
Does any one know?

[Wet Dream]

I did a similar post a while back and I was surprised to learn that it isn't an RPM issue, but a HP issue. The numbers that stuck out for me was 400 hp is moving 4000gpm, give or take a 5 gallon bucket or 2. Thats a whole lot of water.

[gotdamp]

Wet Dream:
I did a similar post a while back and I was surprised to learn that it isn't an RPM issue, but a HP issue. The numbers that stuck out for me was 400 hp is moving 4000gpm, give or take a 5 gallon bucket or 2. Thats a whole lot of water.:)

[gotdamp]

Wet Dream:
I did a similar post a while back and I was surprised to learn that it isn't an RPM issue, but a HP issue. The numbers that stuck out for me was 400 hp is moving 4000gpm, give or take a 5 gallon bucket or 2. Thats a whole lot of water.I don't understand how HP and not rpm determines flow through a pump. HP controls rpm, but rpm, impeller cut and pump type/setup should determine flow (gpm). I am no help, however, in answering the question of approximately how much flow for his setup and rpms. Sorry.

[LVjetboy]

Actually, gpm directly related to nozzle size and pressure. Pressure is a function of rpm and pump design. And hp drives rpm. So flow through pump is equally dependent on either rpm OR hp...neither being independent or a more important issue than the other.
jer
[ August 10, 2002, 11:55 PM: Message edited by: LVjetboy ]

[Wet Dream]

I don't make the charts, I just read them.
http://www3.telus.net/spectrasonly/ATJ.berkeleyspecs.bmp

[diggler]

Interesting. for a 350hp engine, the GPM for a Berkeley is 3,905gpm.
This is a little more than 63.5gallons per SECOND! Wow, that seems high to me, but who am I to say.
I see everyone's problem with this. If I have a 350hp engine and it's just sitting there at idle, I seriously doubt that I pushing 63.5 gallons out of the nozzle. I would have to assume this would be at WOT, or >5000rpm. What does anyone think about this?

[gotdamp]

Wet Dream:
I don't make the charts, I just read them.
http://www3.telus.net/spectrasonly/ATJ.berkeleyspecs.bmpThis chart is for relative comparison purposes only. It is a more practical explanation of flow for somebody that wants to compare one pump vs. another for a given engine. I think they are assuming the A2 and the AA are the exact same cut, in which case rpm could be assumed to be the same for each HP increment in order to compare pump efficiencies.

[Wet Dream]

Just from common sense, the flow rate would be at the peak HP, regardless of RPM. A 500HP engine sure as hell isn't making 500HP at idle is it??? I'm sure the numbers are inflated, but you get a general idea.

[jweeks123]

according to the chart, the Turbine gpm is .3% higher than Berk at 325 and 450 hp. that is a very small difference and very difficult to measure accurately.
jw

[LVjetboy]

WetDream, thanks for posting the charts...saw the left one in HB, but the right one new to me. My comments above were directed at a single pump type: relating rpm (or hp) to gpm...as I understood SeaSlut's original question. Not necessarily comparing two different pump manufacturers or efficiency. But you have a good point about pump efficiency influencing hp versus rpm. So in comparing two different pumps, with different size impellers, hp can be a ruler to measure effiency.
Now let's look at those charts...
The data on the left (published in HB) shows rpm versus mph for the same hull and engine. Dom AA compared to ATJ 9.25. Now rpm depends on both hp and impeller size. The Dom AA large diameter is 9" compared to the ATJ 9.25 impeller large dia. of 9.25. And the Dom AA small dia. is 7 13/16 compared to the ATJ small dia. of 8 1/4. Not necessarily an equal comparison based on size or rpm, as ATJ's larger impeller absorbs more hp at each rpm data point, which gives more speed. Something I think Gotdamp refered to. A better comparison may've been ATJ's AA or A impeller, which is closer in size to Dom's AA impeller. Not knocking ATJ, just that their comparison for less than full throttle data points is somewhat misleading...as would be for example, comparing a Dom AA hull speed to a Dom B speed at the same rpm on the same hull and engine config.
Now for the full-throttle data point. Assuming you accept their data (test conditions identical and such}, a 4 mph advantage goes to ATJ. This may be from a better match to the engine power curve and/or better blade efficiency for the larger impeller at these high rpm's. But I think they stacked the deck by picking an engine with big balls, the sort that loves a big impeller...bigger than what Dom offers. After all, 6100 on an ATJ 9.25 is over 900 hp!
Then they qualify by stating, "Comparison based on each company's most efficient impeller." True, but possibly misleading the reader to believe these same results will hold for the typical lake jet and engine combo that most here run.
Ok, so let's look at the right side. Here's a test of ATJ's AA (large dia. 9 3/32 small 7 13/16) compared to Berkeley AA (large 9, small 7 7/16) again, not the same size although from the "AA" designation, the reader's led to believe an equivalent comparison. As jweeks123 points out, a small diffence, but still measured throughout the range tested...again, assuming their data is correct.
But the real story here may be to use the largest impeller you engine can handle, no matter the manufacturer, until any efficiency gain is far outweighted by the drop-off in hp depending on your engine power curve.
jer